11 107 
Judging from the material at hand, and after having examined the original 
specimens in the British Museum, I cannot see that there is any difference between 
Gray’s two species A. amabaeus and A. dryas (some specimens from Koh Mesan 
agree almost completely with Rerve’s A. dryas). The hinge in the species we are 
here considering presents a peculiar feature, which may be seen in Pl. 1, Fig. 4; 
there is, in the upper valve a keel which extends internally from the point of 
attachment of the ligament to the dorsal margin of the valve, a similar case I 
have neither met with, nor seen described, in any other species of Anomia. The 
umbones are situated at some distance from the margin of the valves. 
Anomia (Aenigma) aenigmatica, Ch. 
Tellina aenigmatica, CHEMNITZ, Conchyl. Cabin., XI, 1795, p. 211, pl. 199, figs. 1949—50. 
Anomia = — Anton, Archiy f. Naturgesch., III Jahrg. 1 Bd., 1837, p. 285, No. 13. 
— cenigmatica, — REEVE, Conchol. icon., XI, 1859, Anomia, Sp. 37. 
s= — = Gray, Proc. Zool. Soc. London, XVII, 1849, p. 118. 
— — - — Catal. Biv. Moll. Brit. Mus., I, 1850, p. 20. 
— — Moetet, Journ. de Conchyl., vol. 37, 1889, p. 160. 
Aenigma = — G. C. Bourne, Quart. Journ. of Microscop. Science, No. 202, 1907, pp. 
253—95, pl. 15—17. 
— roseum, Gray, Martini u. Cuemnitz, Conchyl. Cabin., VII, 1. Abth., p. 62, pl. 7, figs. 1—7. 
— reliculatum, Kocu, Martini u. CHEMNitTz, Conchyl. Cabin., VII, 1. Abth., p. 62, pl. 7, fig. 8. 
-- convexum, — _— - — -- — p. 63, pl. 7, figs. 9—12. 
— corrugatum, — — - - _ —_ _ p- 63, pl. 7, figs. 13—15. 
“Palmiers d’eau a Kanipot (9: Kampot) Golfe de Siam” (L. Moret). 
Distribution:— Singapore, Delta of Irawady (Pegu, Burma), Bombay, Karachi, 
Persian Gulf. — Philippines, Borneo. 
The Danish Expedition to Siam collected no specimens of this species. 
Placuna placenta, L. 
Anomia placenta, Linxnté, Systema Naturae, ed. X, 1758, p. 703, No. 205, ed. XH, p. 1154, No. 241. Mus. 
Ludoy. Ulric, 1764, p. 536, No. 126. 
Placuna — - Lamarck, Hist. nat. d. anim. s. vert., VI, 1 p. 1819, p. 224, No. 3, éd. 2, VII, p. 
270, No. 3. 
-- -— — Encyclop. méthod., pl. 173. 
- Martini u. CHemnirz, Conchyl. Cabin., VII, 1. Abth., p. 66, pl. 5, fig. 3. 
— _ — Reeve, Conchol. icon., XVII, Placuna, Sp. 3. 
P. FiscHer, Catalogue d. Moll. de l’Indo-Chine, p. 208. 
= — — Hornet, Rep. Ceylon Mar. Biolog. Laboratory, I, p. 2. 1906, p. 41. 
Placenta orbicularis, Revzius, Diss. sist. nova testaceorum genera. Lund, 1788, p. 15. 
—_ —_ — MELVILL and STANDEN, Proc. Zool. Soc. London, 1906, p. 793. 
Off Koh Kam, 10 fathoms, gravel (‘/2). S. of Koh Samit, 20 fathoms, mud (2/2). 
W. of Koh Chang, 20 fathoms, mud (1). Sound of Koh Chang, 3—5 fathoms, soft 
clay (many specimens). Coast of Lem Ngob (3). S. of Koh Kut, 17—20 fathoms, 
mud (2). N. of Koh Kong, 8 fathoms, mud (4). 
“Les gréves du golfe de Siam” (MoRLET). 
