31 127 
does not represent Arca indica, Gm., more probably it is A. campechensis, Gm. 
(= A. americana, Gray). Lamarck has also, undoubtedly, been mistaken with 
regard to A. indica, Gm. when, in his diagnosis, he says ‘testa ovata” and later on 
“costiis mediis sulco divisis.” Ep. v. MARTENS also supposes (as he writes in a 
letter to me) that Lamarck has fallen into the same error as REEveE, and has had, 
for examination, a specimen of A. campechensis, Gm. 
Arca (Trisidos) tortuosa, L. 
Arca tortuosa, Linnt, Systema. Naturi, ed. X, 1758, p. 693, No. 1389. — ed. XI], p. 1140, No. 168. — ed. 
XII, p. 3305, No. 1; — Mus. Ludov. Ulr., p. 517, No. 89. 
— — -- LaMARCK, Anim. s. vert., éd. 2, VI, p. 460, No. 1. 
= — —_— ReEEveE, Conchol. icon., [I, Arca, Sp. 86. 
= _ — Martini u. CHEMNITZ, Conchyl. Cabin., VIII, 2 Abth., p. 7, pl.1, figs. 1—2. 
— Crosse et FiscHer, Journ. de Conchyl., vol. 37, 1889, p. 291. 
Parallelipedum tortuosum, Linné, Moruet, Journ. de Conchyl., vol. 37, 1889, p. 163. 
Arca (Parallelepipedum) tortuosa, Linnt, Lamy, Journ. de Conchyl., vol. 55, 1907, p. 108. 
— ftorla, Srernsrrup, Morcu, Catal. conchyl. que reliq. C. P. Kierulf, 1850, p. 33. — Catal. conchyl. 
que reliq. Yoldi, II, 1853, p. 40. 
NW. of Koh Chang, 10 fathoms, mud (1). Koh Lan, 30 fathoms, mud (1). 
W. of Koh Kut, 15 fathoms, mud ('/2). Between Koh Kahdat and Koh Kut, 6—10 
fathoms, clay mixed with sand, shells (1 + 7/2). 
Islands in the Gulf of Siam (Mor ter). 
Long. 10—28 mm. 
Distribution: — Malacca, Singapore, Madras, Gulf of Manaar, Bombay, 
Karachi, Persian Gulf, Gulf of Aden, Zanzibar. — Poulo Condor, Annam, China, 
Philippines, Banka-Strait, Moluccas, North-west Australia, Port Curtis (ast Australia). 
Ep. SmitH! is justified in rejecting KLeIn’s name for the subgenus Parall- 
elepipedum, as it dates from 1753; but he should use BOLTEN’s name Trisidos, dating 
from 1798, and should not employ, as he does, OKEN’s name Trisis, dating from 1815. 
Arca (Trisidos) semitorta, Lam. 
Area semi-torta, LAMARcK, Anim. sans vert., éd. 2, VI, 1835, p. 460. 
—  semitorta, — Reeve, Conchol. icon., Il, Arca, Sp. 89. 
— (Parallelepipedum) semitorta, LAMARcK, Martini u. CHEMNITZ, Conchyl. Cabin., VII, 2 Abth., p. 134, 
pl. 35, figs. 1—2. 
— (Trisis) semitorta, Lamarck, Epa. A. Smirn, Report Challenger Lamellibr., p. 268. 
— (Parallelipipedum) semitorta, LAMARcK, CrossE et FiscHer, Journ. de Conchyl., vol. 40, 1892, p. 76. 
= = — — Lamy, Journ. de Conchyl., vol. 55, 1907, p. 109. 
Common between Koh Rin and Koh Kut, 1—38 fathoms, mud, sand and shells. 
The Gulf of Siam on the west coast of Cambodge (Crosse & FiscieEr). 
Long. 4-83 mm. 
* Report on the Lamellibranchiata of the Challenger-Expedition, p. 268. 
