ホモニム（異物同名）Pleurodon Wood, 1840とPleurodon Harlan, 1842

異なる生物に同じ名前が付いていると混乱が生じます。学名の場合、原則として古い方の適格な名称を使うことになっています。

Pleurodon Wood, 1840とPleurodon Harlan, 1831[1842]の場合はどうでしょうか？
波部(1977)、Treatise on Invertebrate Paleontology、WoRMS等に従えば
Pleurodon (m.) Wood, 1840, n.s., 4: 230-231, type species (M) Pleurodon ovalis Wood, 1840, n.s., 4: 230-231, suppl. pl. 13, fig. 1, non Pleurodon Harlan, 1831, 6(2): 284, Mamm.; Nucinellidae. Gr. pleura; Gr.odous,dens (Herrmannsen, 1847, 2: 297). 側歯（鉸歯は一見多歯型なのに側歯を持つ）；キビガラガイ科　12
ということになりますが、本当にPleurodon Wood, 1840は使えないのでしょうか。

国際動物命名規約第53条2項では属の同名（ホモニム）とは、複数の適格名であって同一の綴りで設立されたもの、とされています。
では、Pleurodon Harlan, 1831は適格名でしょうか。

Harlan (1831: 283-284; republication in 1835)では、Megalonyx laqueatusの記事の中で、「もし今後全体の骨格が発見され、属の区別をすることになった場合、その歯の正中観mesial aspectが肋の有る、或は縦溝を彫られた状態であることに注目したAulaxodon又はPleurodonのどちらでも適切な名前であろう」とのべています。“縦溝のある歯”がAulaxodonとPleurodonのどちらかの名前を定義するものではないので、これら2つの新名は不適格です。


Harlan, 1931, pp. 283-284.

Owen (1840: 66)は”Dr. Harlan does not enter into the question of the generic characters of Megalonyx, but it would seem that he felt them to rest not entirely on detail modification …”と述べ、Palmer (1904: 818)はPleurodon Harlan, 1931を“Name suggested, but not used, in place of Aulaxodon Harlan, 1830”と書いている[蛇足: 1830は1831の誤り]。どちらもPleurodonが明確に提唱されたとは考えていません。

Vokes (1980: 22)はPleurodon Wood, 1840, Mag. nat. Hist., (N.S.) 4: 230 [non Harland, 1834 (Mamm.); see Nucinella Wood, 1851]と書き、Nucinella Wood, 1851, Monogr. Crag Moll. (Palaeontogr. Soc. Monogr.) (2): 72 [n.n. pro Pleurodon Wood, 1840]を有効な名称としています。

Harlanの論文を集めた著作集(Harlan, 1935)では、Pleurodonと言う名称が出てくるのはHarlan (1831)だけです。Pleurodon Harlan, 1834というのはH. E. Vokes教授の勘違いかもしれません。

Agassiz (1847)のNomenclator zoologicusではPleurodon Harl. in Sill. Am. Jour. [American Journal of Science and Arts, conducted by Professor Silliman and Benjamin Silliman, Jr., vol.] XLIII, 1842. Gr. pleura, latus; Gr. odous, dens. = Mylodon.-Edent.とされています。

Harlan (1842: 141-142)は、Mylodon（臼歯）という属名は特有の性質を示すものではなく、化石哺乳類のどれにでも通用する名称である、これに対してPleurodon（縦溝の彫られた歯）はMylodon harlani, Megalonyx jeffersonii, Megalonyx laqueatus, Mylodon darwiniiに適用される特有の性質を表す名称であると述べ、ここでPleurodonが正式に適格になったと考えられます。

今後、Vokes (1980)のいうPleurodon Harlan, 1934が見つかる可能性がありますが、現段階ではPleurodon Wood, 1840はPleurodon Harlan, 1842の古参ホモニムであり、有効な名称であると考えるのが良いようです。

Lexicon generum bivalvium-Pleurodon
Pleurodon (m.) Wood, 1840, n.s., 4: 230-231, type species (M) Pleurodon ovalis Wood, 1840, n.s., 4: 230-231, suppl. pl. 13, fig. 1, non Pleurodon Harlan, 1831, 6(2): 284, nomen nudum (Palmer, 1904: 818); Harlan, 1842, 43(1): 141-142, Mamm.; Nucinellidae. Gr. pleura; Gr. odous,dens (Herrmannsen, 1847, 2: 297). 側歯（鉸歯は一見多歯型なのに側歯を持つ）；キビガラガイ科

新年会；Lexicon generum bivalvium (T, U)

今日は我らがふれあいテニスクラブの新年会。プレイ＆畑はお休みです。
____________________________________________________
T
Tagelus (m.) Gray, 1847, (15), for 1847: 189, type species (OD) “Sol. guinensis” [non Solen guinensis Hanley, 1842: 12], pro “Solen tagel [tagal] Adanson, 1757: 255-257, pl. 19, fig. 1” of Gray, 1847, = Solen adansonii Bosc, 1801, 3: 12, ref. Adanson, 1757, pl. 19, fig. 11 [1]; Solecurtidae. Le Tagal, vernacular name for a kind of mussel in Senegal, adopted by Adanson (1757). アダンソンが使ったセネガルの土語le Tagalに由来；キヌタアゲマキガイ科

Talabrica (f.) Iredale, 1924, 49: 181, 204, type species (OD) Crassatella aurora A. Adams & Angas, 1863, for 1863: 426-427, pl. 37, fig. 15, Tasmania; Crassatellidae. Talabriga, proper name (Otsuka et al., 1969), ancient Roman city in Portugal (https://en.wikipedia.org/wiki/Roman_cities_in_Portugal). 固有名詞（ポルトガルにあったローマ時代の都市）；モシオガイ科サガミモシオガイ属 163

Tancredia (f.) Lycett, 1850, [2], 6: 407-408, type species (SD Morris & Lycett, 1854[1855?], 8(28): 91) Tancredia donaciformis Lycett, 1850, [2], 6: 424, pl. 11, fig. 8, Middle Jurassic, Europe; Tancrediidae. Dedicated to Sir Thomas Tancred, Bart., founder of the Cotteswold Naturalists’ Club (Woodward, 1868: 457). 準男爵トーマス・タンクレッド卿に因む；タンクレッド科

Tanysiphon (m.) Benson, 1858, [3], 1: 408, type species (M) Tanysiphon rivalis Benson, 1858, [3], 1: 408-409, pl. 12B, figs. 1-3; Glauconomidae. tany-, from Gr. tanyo, stretch out, long (Brown, 1956); Gr. siphon, o, a tube, pipe, siphon (Liddle & Scott, 1955). 長い水管； ハナグモリガイ科ハナグモリガイ属 277

Tapes (m.) Megerle von Mühlfeld, 1811, 5(1): 51, type species (M) Venus literata Linnaeus, 1758, ed. 10, 1: 689; Veneridae. L. tapes, etis, m., tapestry, carpet; die Mattenmuschel (Megerle von Mühlfeld, 1811, 5(1): 51) つづれ織り・絨緞、或は莚・茣蓙の二枚貝；マルスダレガイ科リュウキュウアサリ属 263

Tegillarca (f.) Iredale, 1939, 5(6), Moll., pt. 1: 274, 281, type species (OD) Tegillarca bessalis Iredale, 1939, 5(6), Moll., pt. 1: 282-283, Recent, northeast Australia; Arcidae. L. tegillum, i, n., a small covering, a hood or cowl (W. Smith & Lockwood, 1976); Arca Linnaeus, 1758, ed. 10, 1: 693. 小さな覆い、フード、（修道士の）頭巾（付き外衣）のフネガイ類；フネガイ科ハイガイ属

Telemactra (f.) Iredale, 1929, 9(3): 268, type species (OD) Mactra obesa Reeve, 1854, 8: Mactra pl. 5, sp. 19, Torres Straits; Mactridae. tele-, Gr. teleios and Gr. teleos, having reached its end, full-grown (Liddell & Scott, 1955); Mactra Linnaeus, 1767, ed. 12, 1(2): 1125. 成熟したバカガイ類；バカガイ科ヒメバカガイ属 179

Tellidora (f.) H. & A. Adams, 1856, 2: 401, type species （SD Stoliczka, 1871, 3: 116） Tellina burneti Broderip & G. B. Sowerby I, 1829, 4(15): 362, pl. 9, fig. 2; Tellinidae. Having the aspect of a Myodora　[= Myadora Gray, 1840, [1], 4(15): 306], but with the teeth of the hinge as in Tellina (H. & A. Adams, 1856, 2: 401). Myodoraの見掛けとTellinaの歯を持つ貝；ニッコウガイ科

Tellimya (f.) Brown, 1827, ed. 2: ind. ii, expl. of pl. 14, figs. 10-21, pl. 16, fig. 23, type species (SD Gray, 1847, (15), for 1847: 192, as Mya ferruginea) Mya ferruginosa Montagu, 1808: suppl. 22, pl. 26, fig. 2; Montacutidae. Tellina;Gr. myax. Tellinaのような二枚貝;ブンブクヤドリガイ科ニヨリブンブクヤドリガイ属 146

Tellina (f.) Linnaeus, 1758, ed. 10, 1: 674, type species (SD Children, 1823, 14(28): 306) Tellina radiata Linnaeus, 1758, ed. 10, 1: 675, no. 42; Tellinidae. Gr. telline, sorte de coquillage (Athénée), the Greek name for a kind of mussel (Woodward, 1868: 480; Fischer, 1887: 1147). ある種の二枚貝の古名；ニッコウガイ科

Tellinella (f.) Mörch, 1853, (2): 13, type species (SD Stoliczka, 1870: 116) Tellina virgata Linnaeus, 1758, ed. 10, 1: 674, no. 35; Tellinidae. Tellina Linnaeus, 1758; -ella. 小型のニッコウガイ類；ニッコウガイ科ニッコウガイ属 192

Tellinides (m.) Lamarck, 1818, 5: 535, type species (M) Tellinides timorensis Lamarck, 1818, 5: 536; Tellinidae. Dim. of Tellina (Chenu, 1847a: 62; 1847b: 142). 小さなニッコウガイ類；ニッコウガイ科ヘラサギガイ属 194

Tellinimactra (f.) Lamy, 1918b, 24(3): 169, type species (OD) Tellina edentula Spengler, 1798, 4(2): 96-98; Tellinidae. Tellina Linnaeus, 1758, ed. 10, 1: 674; Mactra Linnaeus, 1767, ed. 12, 1(2): 1125. TellinaとMactra；ニッコウガイ科タイワンシラトリガイ属 212

Tellinula (f.) Mörch, 1853, (2): 14, [objective junior synonym of Fabulina Gray, 1851, (7): 40, type species (SD Winckworth, 1932, Jour. of Conch., 19(7): ) Tellina fabula Gmelin, 1791, ed. 13, 1(6): 3239, no. 61]; Tellinidae. Tellina Linnaeus, 1758, ed. 10, 1: 674; -ula. 小さなTellina；ニッコウガイ科 207

Tellinungula (f.) Römer, 1873, 10(4), pt. 217: 268, type species (M) Tellina bruguieri Hanley, 1844, pt. 12, for 1844: 142 [objectice junior synonym of Macalia H. Adams, 1861, pt. 28, for 1860: 369]; Tellinidae. Tellina Linnaeus, 1758, ed. 10, 1: 674; L. ungula, ae, f., a claw, talon, hoof (W. Smith & Lockwood, 1976). 蹄のようなニッコウガイ類；ニッコウガイ科 212

tellus L., f., uris, the earth, globe (Lewis, 1915). 地球、大地

Tentidonax (f.) Iredale, 1930, 17(9): 398, type species (OD) Donax veruinus Hedley, 1913, 38: 274-275; Donacidae. L. tentus, adj. A, stretched out (W. Smith & Lockwood, 1976); Donax Linnaeus, 1758, ed. 10, 1: 682. 引き伸ばされたナミノコガイ類；フジノハナガイ科キュウシュウナミノコガイ属 191

Tenuileda (f.) Habe, 1977: 21-23, type species (OD) Nuculana conceptionis ikebei Suzuki & Kanehara, 1936, 43(510): 182-184, pl. 10, figs. 16-18; Nuculanidae. L. tenuis; Leda Schumaher, 1817: 55, 172-173. 薄く弱々しいロウバイガイ類；ロウバイガイ科カゲロウソデガイ属 21

tenuis L. adj. B, drawn out, meagre, slim, thin, lank, slender (Lewis, 1915). 細い、薄い

Tepidoleda (f.) Iredale, 1939, 5(6), Moll., pt. 1: 240, type species (OD) Tepidoleda lata orion Iredale, 1939, 5(6), Moll., pt. 1: 240, pl. 1, figs. 9, 9a; Nuculanidae. L. tepidus, adj. A, moderately warm, faint, languid (Lewis, 1915); Leda Schmacher, 1817: 55, 172-173. ほのかなシワロウバイガイ類；ロウバイガイ科 25

Teredina (f.) Lamarck, 1818, 5: 438, type species (SD Children, 1822, 14(27): 81) Teredina personata Lamarck, 1818, 5: 438; Pholadidae. Dim. of Teredo (Chenu, 1847a: 36; 1847b: 116). 小さなフナクイムシ類；ニオガイ科テレディーナ属

Teredo (f.) Linnaeus, 1758, ed. 10, 1: 651, type species (SD Children, 1822, 14(27): 82; Hemming, 1957e, 1E: 161-192, Direction 72; Hemming, 1957e, 1E: 195-211, Direction 73; Hemming, 1958, 1B, Opinion 94: 348-349) Teredo navalis Linnaeus, 1758, ed. 10, 1: 651; Teredinidae. Teredo, ver perforant (Chenu, 1847a: 36; 1847b: 116); nom donné par Pline à un ver qui ronge le bois (Fischer, 1887: 1138). 木を食う貝に対してプリニウスが名付けた名前；フナクイムシ科フナクイムシ属

Teredops (f.) Bartsch, 1921, 34(1): 26, type species (OD) Teredo diegensis Bartsch, 1916, 30(4): 47-48; Teredinidae. Teredo Linnaeus, 1758, ed. 10, 1: 651; ops. フナクイムシ属の外見をしたもの；フナクイムシ科

Teredora (f.) Bartsch, 1921, 34(1): 26, type species (OD) Teredo malleolus Turton, 1822: 255-257, pl. 2, fig. 19. Teredo Linnaeus, 1758; -ora, Gr. opas.　　フナクイムシ属に似たもの；フナクイムシ科コチョウフナクイムシ属

Teredothyra (f.) Bartsch, 1921, 34(1): 26, type species (OD) Teredo　（Teredothyra） dominicensis Bartsch, 1921, 34(1): 30-31; Teredidae. Teredo Linnaeus, 1758, ed. 10, 1: 651; Princess Thyra of Denmark (1853-1933). チューラ女王のフナクイムシ；フナクイムシ科 299

Terua (f.) Dall, Bartsch & Rehder, 1938, (153): 57-58, type species (OD) Terua pacifica Dall, Bartsch & Rehder, 1938, (153): 58, pl. 11, figs. 11-14; Mytilidae. Terua, a genus of legume (Fabaceae). マメ科植物の属名；イガイ科ヒラノマクラガイ属 63

Tetrarca (f.) Nordsieck, 1969: 20, type species (OD) Arca tetragona Poli, 1795, 2: 137-138; Arcidae. tetragona; Arca Linnaeus, 1758, ed. 10, 1: 693. 29

tetragonus Gr. tetragonos, with four equal angles, square (Liddell & Scott, 1953). <四角形の>　　例：Arca tetragona Poli, 1795, 2: 137-138.

Textrix (f.) Römer, 1857: 16, type species (M) Venus textile Gmelin, 1791, ed. 13, 1(6): 3280 [non Textrix Blackwall, 1833, [3], 3(14): 108-109, Arach., nec Sundevall, 1833, Consp. Arach. (fide Agassiz, 1846, Nom. Syst. Gen. Arach.: 13), Arachn.; see Paratapes Stoliczka, 1870, 3: 144]; Veneridae. L. textilis, adj. B, textile, woven (Lewis, 1915). 織物模様のある貝；マルスダレガイ科（サラサスダレガイ属）265

Thecodonta (f.) A. Adams, 1864b, [3]13: 308-309, type species (M) Thecodonta sieboldi A. Adams, 1864b, [3]13: 309, Goto Islands, the Sea of Japan; Montacutidae. Gr. theke, [L. thecas] a box, chest, a case to put　anything in (Liddell & Scott, 1953); Gr. odous. 箱形の歯；ブンブクヤドリガイ科コメガイ属 148

Theora (f.) H. & A. Adams, 1856, 2: 369-370, type species (SD Stoliczka, 1871, 3: xvii) Neaera lata Hinds, 1843, pt. 11, for 1843: 79; Semelidae. 　Inconnue; Gr. Theora, je regarde? (Fischer, 1887: 1152), or Gr. theoros, a spectator, an ambassador sent to consult an oracle or to present an offering (Liddell & Scott, 1955). 語源不詳、私は見ている（？）、聴衆、神託を聞くため（或は捧げものをするため）に使わされた使者；アサジガイ科シズクガイ属 218

Thestyleda (f.) Iredale, 1929, 17(4): 158, type species (OD) Leda ramsayi E. A. Smith, 1885, 13(35): 241, pl. 20, figs. 3-3a; Nuculanidae. Thesty, a name of person; Leda Schumacher, 1817: 55, 172-173. Thestyのロウバイガイ類；ロウバイガイ科アラボリロウバイガイ属 21

Thetirobia (f.) Stoliczka, 1870, 3: 158 [new name pro Thetis J. de C. Sowerby, 1826, non Oken, 1815: 280-282], type species (SD Stoliczka, 1870, 3: 158) Thetis minor J. de C. Sowerby, 1826, 6: 21-22, pl. 513, figs. 5-6; Mactromyidae. Thetis J. de C. Sowerby, 1826; Robia, feminine given name. ThetisのRobia；マクトロミア科

Thetis (f.) J. de C. Sowerby, 1826, 6: 19 [non Oken, 1815: 280-282], type species (SD Woodward, 1868: 491) Thetis minor J. de C. Sowerby, 6: 21-22, pl. 513, figs. 5-6 [= Corbula laevigata J. Sowerby, 1818, 3: 14, pl. 209, figs. 1-2]; Mactromyidae. Gr. Thetis, in Greek mythology, a sea-nymph (Woodward, 1868: 491), the name of beautiful Sea Nymph (J. de C. Sowerby, 1826, 6: 19). ギリシャ神話の海の妖精テーチス；マクトロミア科

Thracia [W. E. Leach in J. de C. Sowerby, 1823, 5(72): 20, n.n.] Blainville, 1824, 32: 347, type species (SD Blainville, 1829, 54: 314; Herrmannsen, 1849, 2: 574; non Anton, 1839: 2, expl. Amphidesma phaseolina Lamarck, 1818, 5: 492 and Thracia pubescens “Lamarck”) Mya pubescens Pulteney, 1799, Catal. birds, shells, &c. of Dorsetshire: 27 (fide Sherborn, 1902: 783); Thraciidae. Gr. Thracios, of or belonging to Thracians, Thracian (Liddell & Scott, 1953), de Thrace (Fischer, 1887: 1170). トラキア人（の）；スエモノガイ科スエモノガイ属 311

Thracia J. de C. Sowerby, 1823, 5(72): 20, nomen nudum; authorship of Mineral Conchology, vol. 5 attributed to James de Carl Sowerby (ICZN, 1987, 44(1), Opinion 1429: 64-67; ICZN, 1988, 45(2), Direction 123: 180).

Thracidora (f.) Iredale, 1924, 49(3): 200, type species (OD) Thraciopsis arenosa Hedley, 1904, 29: 197, pl. 9, figs. 26-27; Thraciidae. Thracia Blainville, 1824; Gr. dora, a skin, hide (Liddell & Scott, 1853). スエモノガイ類の膚；スエモノガイ科ワタゾコスエモノガイ属 312

Thraciokellia (f.) Kuroda & Habe in Kuroda, Habe & Oyama, 1971: 628-629, 405, type species (OD) Thraciokellia jogashima Kuroda & Habe, 1971: 629, 405, pl. 119, figs. 5-6; Lasaeidae. Thracia Blainville, 1824, 32: 347; Kellia Turton, 1822: xix, 56-57. 殻頂部にスエモノガイ類の様な欠刻を持つコハクノツユガイ類；チリハギガイ科スエモノコハクガイ属 143

Thyasira (f.) Lamarck, 1818, 5: 492, type species (M) Tellina flexuosa Montagu, 1803, (1): 72-73. Ethymology unknown. 語源不詳；ハナシガイ科ハナシガイ属 129

Trapezium (n.) Megerle von Mühlfeld, 1811, 5: 68, type species (SD Stewart, 1930, (3): 173) Trapezium perfectum Megerle von Mühlfeld, 1811, 5: 68-69 [= Chama oblonga Linnaeus, 1758, ed. 10, 1: 692]; Trapezidae (ICZN, 1990, 47(3), Opinion 1615: 229-230). Gr. trapezion, trapezium, dim. of trapezia, mensula, a small dining-table (Herrmannsen, 1849, 2: 586; Liddel & Scott, 1940), Gr.trapez, (prob. for Gr. tetra-peza, four-legged) a table, esp. dining-table (Liddell & Scott, 1955). 小卓；フナガタガイ科フナガタガイ属 233

Tresus (m.) Gray, 1853, [2], 11: 42, type species (M) Lutraria maxima Middendorff, 1849, [6], 6(2): 582-583, = Lutraria capax Gould, 1850a, 3(3): 217, Puget Sound; [junior homonym of Lutraria maxima Jonas, 1844, Jahrg. 1844: 34, = Lutraria (Cryptodon) nuttallii Conrad, 1837, 7(2): 235, pl. 18, fig. 1, fide Habe, 1977: 183]; Mactridae. Gr. tresis, a boring, a perforation (Jaeger, 1959). 183

tri- Gr.tri, in compds. three times, thrice, Lat. ter (Liddell & Scott, 1953). ＜3倍の＞

trichos Gr. trichos, gen. of Gr. thrix, the hair, both of man and beast: sheep’s wool: also of the beard (Liddell & Scott, 1953). 人や動物の毛の、羊毛の、顎髭をたくわえた

Trichomusculus (m.) Iredale, 1924, 49(3): 196, type species (OD) Lithodomus barbatus Reeve, 1858b, 10: Lithodomus pl. 5, sp. 27, Sydney; Mytilidae.　Gr. tricha or Gr. triche, adv. threefold, in three parts (Liddell & Scott, 1953); Musculus [Röding, 1798, (2): 156]. 殻皮が牡鹿の角のように分岐して、殻表が3分されて、又は毛の生えたタマエガイ類；イガイ科スジタマエガイ属 56

Trichomya (f.) Ihering, 1900, 4: 87, type species (OD) Mytilus hirsutus Lamarck, 1819, 6: 120, Australia.  [trichos]; .　　毛の生えた二枚貝；イガイ科ケガイ属 53

Tridachnes (m.) [Röding, 1798], (2): 171, type species (SD Iredale, 1937, 8(4): 236) Chama gigas Linnaeus, 1758, ed. 10, 1: 691; objective junior synonym of Tridacna Bruguière, 1797, 2: pls. 235-236; Tridacnidae. For the etymology, see Tridacna. 175

Tridacna (f.) Bruguière, 1797, 2: pls. 235-236, type species (SD Lamarck, 1799, an 7: 86) Chama gigas Linnaeus, 1758, ed. 10, 1: 691; Tridacnidae. (1) Nom ancien de certaines Huitres, a kind of oyster (Pliny) (Chenu, 1847a: 86; 1847b: 166; Woodward, 1868: 452; Tryon, 1884, 3: 208; Fischer, 1887: 1034); tri-, three; dakno, to bite (Woodward, 1868: 452; Tryon, 1884, 3: 208). プリニウスが使ったある種の二枚貝の名前、語意は三度噛むこと（殻の大きな襞に因む）；シャコガイ科オオシャコガイ属 175

Tridonta (f.) Schumacher, 1817: 49, 146, type species (M) Tridonta borealis Schumacher, 1817: 147, pl. 17, fig. 1; Astartidae. Tris; Gr. odon, dens. 3本の歯；エゾシラオガイ科エゾシラオガイ属　 160

Trifaricardium (n.) Kuroda & Habe, 1951, (13): 86 (25 June); Kuroda & Habe in Habe, 1951, (3): 152-153 (15 Oct.), type species (M) Trifaricardium nomurai Kuroda & Habe, 1951, (13): 86; Cardiidae. L. trifarius, adj. A, arranged in three ranks (Stearn, 1983); Cardium Linnaeus, 1758, ed. 10, 1: 678. 殻表中後部には対をなす放射肋があり、その間から小棘が出るザルガイ類；ザルガイ科オトヒメザルガイ属 170

Trigona (f.) Megerle von Mühlfeldt, 1811, 5: 55 [non L. Jurine, 1807: 245], type species (SD Gray, 1847, (15), for 1847: 183) Venus mactroides Born, 1778: 52; Veneridae. Gr. trigonos. 三角形の貝；マルスダレガイ科

Trigonella (f.) da Costa, 1778: 196 [non Bertrand, 1763, 2: 229, included in a work rejected for nomenclatural purposes (Melville & J. D. D. Smith, 1987: 317); Melville, 1959, 17: 49-53], type species (SD Winckworth, 1926, 17: xx103-106) Cardium stultorum Linnaeus, 1758, ed. 10, 1: 681 [= Mactra stultorum (Linnaeus, 1758); Linnaeus, 1767, ed. 12, 1(2): 1126) [objective junior synonym of Mactra Linnaeus, 1767, ed. 12, 1(2): 1125]; Mactridae.  [trigonos]; -ella. 小さな三角形の貝；バカガイ科 178

Trigonia (f.) Bruguière, 1789, 1(1): xiv, type species (designation under the ICZN Plenary Power, Hemming, 1955a, 9(19): 285-298, Opinion 327) Venus sulcata Hermann, 1781, 15: 127-129, pl. 4, figs. 9-10; Trigoniidae. Gr. trigonos, trigone (Chenu, 1847a: 77; 1847b: 157), three-angled (Woodward, 1868: 430). 三角貝；サンカクガイ科サンカクガイ属 122

Trigoniocardia (f.) Dall, 1900c, 3(5): 1075, type species (OD) Cardium graniferum Broderip & G. B. Sowerby I, 1829, 4: 367; Cardiidae. Trigonia Bruguière, 1789, 1(1): xiv; Cardium Linnaeus, 1758, ed. 10, 1: 678. 三角貝のようなザルガイ類；ザルガイ科 168

trigonosGr. trigonos, three-cornered, triangular; to, a triangle (Woodward, 1868: 474; Liddell & Scott, 1955). （形）三角形の、（名）三角形

Trigonothracia (f.) Yamamoto & Habe, 1959, Bull. Mar. Biol. Stat. Asamushi, 9(3): 117, type species (OD) Thrachia (Trigonothracia) nomurai Yamamoto & Habe, 1959, 9(3): 117-118, pl. 12, figs. 9-10 [= Thracia pusilla Gould, 1861, 8: 23, Shimoda]; Thraciidae. Trigonia Bruguière, 1789, 1(1): xiv; Thracia Blainville, 1824, 32: 347. 三角貝のようなスエモノガイ類；スエモノガイ科ノムラスエモノガイ属 312

Triomphalia (f.) G. B. Sowerby II, 1849b, 2(10): 500-501, type species (SD G. B. Sowerby II, 1850, pt. 17, for 1849: 160) Triomphalia globosa G. B. Sowerby II, 1849b, 2(10): 501, pl. 106, figs. 54-55 [= Pholas globulosa Quoy & Gaimard, 1835, 3(2): 549-550 (1835), pl. 85, figs. 16-19 (1833); non Pholas globosa Schröter, 1801, 2(1): 108]; Pholadidae. The name is taken from the nucleus of the anterior lamina, which, overlying the two umbones, forms as it were, a third (G. B. Sowerby II, 1849b, 2(10): 501); tri-, Gr. treis, L. tres, tria, three (Liddell & Scott, 1955); Gr.omphalos, umbo (G. B. Sowerby II, 1850, pt. 17, for 1849: 160), the navel （Jaeger, 1959）. ３つの殻長；ニオガイ科 293

Triquetra (f.) Blainville, 1828, 55: 359, type species (SD Anton, 1839: 10) Venus flexuosa Linnaeus, 1767, ed. 12, 1(2): 1131 [objective junior synonym of Anomalocardia Schumacher, 1817: 44-45, 134-135]; Veneridae. L. triquetrus, adj. A, three-cornered, triangular (W. Smith & Lockwood, 1976). 三角形の貝；マルスダレガイ科 115

Trisidos (f.) [Röding, 1798], (2): 175, type species (M) Trisidos tortuosa [Röding, 1798], (2): 175 [= Arca tortuosa Linnaeus, 1758, ed. 10, 1: 693]; Arcidae. Gr. tris, Lat. tres, three (Liddell & Scott, 1953); Gr. idos, that which is seen, the form, shape, figure, Lat. species (Liddell & Scott, 1953). 3面を持つ（もの）；フネガイ科ビョウブガイ属 32

Trisis (f.) Oken, 1815, 3, Zool.: 236 [invalid ICZN Op. 417]; Blainville, 1825: 535, type species (M) Arca tortuosa Linnaeus, 1758, ed. 10, 1: 693; Arcidae. L. adj., tres, treis, tris, three, Gr. tris (W. Smith & Lockwood, 1976); -is, L. and G. adj. suffix, indicates a close connection, noun base (Brown, 1956; Stearn, 1983). 3面を持つ（もの）；フネガイ科ビョウブガイ属

Tuceta (f.) [Röding, 1798], (2): 172, type species (SD Dall, 1909, (59): 107) Arca pilosa Linnaeus, 1758, ed. 10, 1: 695; objective synonym of Glycymeris da Consta, 1778: 168; Glycymerididae. L. tuccetum or tucetum, i, n., a kind of sausage or haggis (Herrmannsen, 1849, 2: 635; W. Smith & Lockwood, 1976). ある種のソーセージ；タマキガイ科 45

Tucetilla (f.) Iredale, 1939, 5(6), Moll. pt. 1: 297, 300-301, type species (OD) Glycymeris capricornea Hedley, 1906, 31: 468-469, pl. 36, figs. 5-6; Glycymerididae. Tuceta [Röding, 1798], (2): 172; L. –illa, diminutive suffix (Jaeger, 1959). 小型のタマキガイ類；タマキガイ科ビロードタマキガイ属 45

Tucetona (f.) Iredale, 1931, 18(4): 202, 231, type species (OD) Pectunculus flabellatus Tenison-Woods, 1878, 14(9): 61-62; Glycymerididae. Tuceta [Röding, 1798], (2): 172; L. –onus, suffix that arguments the force or meaning (Brown, 1956). タマキガイ類；タマキガイ科ウチワガイ属 47

Tucetonella (f.) Habe, 1961, 2: 112, app. 36, type species (OD) Tucetona (Tucetonella) planicostata Habe, 1961, 2: 112, app. 36, pl. 50, fig. 5 [= Pectunculus mundus G. B. Sowerby III, 1903, [7], 12: 501, Hirado, Higen [err. pro Hiz-], Japan]; Glycymerididae. Tucetona Iredale, 1931, 18(4): 202, 231; L. –ella, suffix added noun stems to form diminutives (Jaeger, 1959). 小型のウチワガイ類；タマキガイ科コギツネガイ属 47

Tucetopsis (f.) Iredale, 1939, 5(6), Moll. pt. 1: 302, type species (OD) Cardium amboinense Gmelin, 1791, 1(6): 3255; Glycymerididae. Tuceta [Röding, 1798], (2): 172; Gr. opsis, look, appearance (Liddell & Scott, 1955). タマキガイ類の見掛けをしたもの；タマキガイ科 47

U
-ulus, a, um Latin substantival diminutive suffix (Jaeger, 1959; Stearn, 1983). ラテン語縮意語尾、“姫”、“小さな”

Umitakea (f.) Habe, 1952, (3): 241, type species (OD) Pholadomya japonica Yokoyama, 1920, 39(6): 106-107, pl. 6, figs. 30-31 [= Pholas dilatata Souleyet, 1843, 6: 176-177]; Pholadidae. Umitake, Japanese vernacular name of this species, meaning sea fungi. ウミタケ（海茸）、泥底に深く潜る二枚貝の1種；ニオガイ科ウミタケガイ属 290

Ungoteredo (m.) Bartsch, 1927, 100(2): 544, type species (OD) Teredo (Ungoteredo) matacotana Bartsch, 1927, 100(2): 545, pl. 53, figs. 8-9, pl. 56, fig. 2, pl. 60, figs. 5-7; Teredinidae. L. unguis, is, m., a nail or hoof (G. B. Sowerby II, 1839, ed. 1: 111); Teredo Linnaeus, 1758, ed. 10, 1: 651. 爪のあるフナクイムシ類；フナクイムシ科 299

Ungulina (f.) Bosc, 1801, 3: 76-77, type species (SD de Roissy, 1804, 6: 375) Ungulina rubra de Roissy, 1804, 6: 375; Ungulinidae. Chavan (1969, 2: N515) adopted “SD Gray, 1847: type species U. oblonga Lamarck, 1818, 5: 487 [= U. rubra de Roissy, 1804]. L. ungula, ae, f., a nail, claw, talon, hoof, ongle (G. B. Sowerby II, 1839: 111); ungulina, like a hoof (Woodward, 1868: 458). 爪、蹄に似たもの；フタバシラガイ科 134

Unio (m.) Philippson, 1788: 16, type species (by designation under the plenary power, Hemming, 1957e, 17: 289, 290, Op. 495) Mya pictorum Linnaeus, 1758, ed. 10, 1: 671; Unionidae. L. unio, onis, m., a pearl (Pliny), perle (Chenu, 1847a: 79; 1847b: 159; Woodward, 1868: 433). 真珠；イシガイ科イシガイ属 114

Uperotus (m.) Guettard, 1770, Mémoires sur Diférentes Parties des Sciences et Artes, Paris, 3: 126-128 (fide Turner, 1966: 263), type species (SD Lamy, 1927: 275) Teredo clava Gmelin, 1791, ed. 13, 1(6): 3748; Teredinidae. Gr. uperos, o, malleus quo fores pulsantur (Herrmannsen, 1849: 671), or anything shaped like a pestle, a club, cudgel (Liddell & Scott, 1955). 擂り粉木、こん棒に似たもの；フナクイムシ科ボロウチワフナクイムシ属 301

Ustularca (f.) Iredale, 1939, 5(6), Moll. pt. 1: 248, 268, type species (OD) Ustularca cruciata renuta Iredale, 1939, 5(6), Moll. pt. 1: 268-269, pl. 3, figs. 1, 1a; Arcidae. L. ustulo, are, avi, atum, to burn a little (W. Smith & Lockwood, 1976); Arca Linnaeus, 1758, ed. 10, 1: 693. 少し焦げたフネガイ類；フネガイ科ベニエガイ属 31