15 111 
The northern side of Koh Mesan, 10—15 fathoms, stones (1). S. of Koh Chuen, 
30 fathoms, shells (2). Between Koh Kut and Koh Kahdat, 10 fathoms, shells (7/2). 
Long. 8—23 mm. 
Distribution: — King Island, Mergui Archipel (E. v. MarrEens), Poulo Penang 
(Mus, Calcutta), Bombay (Mus. Calcutta), — Amoy (Jousseaume). 
E. v. Martens! and Lamy refer this species to the subgenus Barbatia. But it 
appears to me that it should be placed with Arca (s. str.), DuNkeR has already 
stated, that the species varies considerably in regard to form, and the specimens 
from the Gulf of Siam, as well as Lamy’s figure, entirely confirm this statement. 
As the specimen figured by DuNKER is rather monstrous I have thought it right to 
give a new figure of a typical specimen. 
Arca (Barbatia) fusca, Brug. 
Arca fusca, BruGuIeRE, Dictionn. eneycl. méthod., I, 1792, p. 102, No. 10. 
- Encyel. méthod., pl. 308, fig. 5 
_ — — Lamarck, Anim. s, vertebres, ed. 2, VI, p. 466, No. 14. 
REEVE, Conchol. icon, II, Arca, Sp. 82. 
— (Barbatia) fusca, BruG., Martini u. CHEMNitz, Conchyl. Cabin., VIII, 2 Abth., p. 18, pl. 4, fig. 2; pl. 6, 
figs. 5—6. 
P. Fiscner, Catal. d. Moll. de l'Indo-Chine, p, 214. 
= = = — Lamy, Journ. de Conchyl., vol. 55, 1907, p. 53. 
—  bicolorata, CuEMNitTz, Conchyl, Cabin., XI, 1795, p. 243, pl. 204, fig. 2007. 
The northern side of Koh Chang, 1 fathom, coral blocks (2/2). Koh Mak, sand 
coast ('/2). Koh Kahdat, 1 fathom, sand (1). 
Long. 12—33 mm. 
Distribution: — Singapore (The Danish Expedit. to Siam, 2 specimens, 2 
fathoms, coral-reef), Mergui Isls., Nicobar Isls., Madras, Gulf of Manaar, Red Sea, 
Seychelles, Madagascar, Mascarenes, Querimba Isls. — Poulo-Condor, Cochin China, 
Philippines, Mentawei Isls., Celebes, Sulu Isls., Java, Small Sunda Isls., Moluccas, 
Aru Isl., Sorong, Torres Strait, North, East and West Australia, Salomo Isls., Viti 
Isls., Tonga Isls., Lifu Isl, New Caledonia, New Zealand. 
Lamy (loc. cit. p. 53) considers A. cruciata, Philippi and A. Rodatzi, Dunker 
(from Zanzibar) to be synonymous with A. fusca, Brug. 
Arca (Barbatia) complanata, Ch. 
(Pl. 1, Figs. 5—10). 
Arca ipa Cuemnitz, Conchyl. Cabin., VII, 1784, p. 198, pl. 55, figs, 544—45. 
a — L. Moret, Journ. de Conchyl., vol. 37, 1889, p. 162. 
-- (Barbatia) complanata, CHEMNITZ, P. FiscHER, Catal. d. Moll. de ?'Indo-Chine, p. 215. 
Byssoarca decussata, SowERBy, Proc. Zool. Soc. London, vol.J, 1833, p. 18. 
Arca = = REEYE, Conchol. icon., If, Arca, Sp. 81. 
1 The Journal of the Linnean Soc., vol. XXI, 1887, p. 207. 
