11 107 



Judging I'roin the material at hand, and after having examined tlie original 

 specimens in the British Museum, I cannot see that there is any dilTerence between 

 Gray's two species A. amahaeus and A. dryas (some specimens from Koh Mesan 

 agree almost completely with Reeve's A. dryas). The hinge in the species we are 

 here considering presents a peculiar feature, which may be seen in PI. 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 Anomin. The 

 umbones are situated at some distance from the margin of the valves. 



Anomia (Aenigma) aenigmatica, Ch. 



Tdlina aenigmatica, Chemnitz, Conchyl. Cabin., XI, 1795. p. 211, pi. 199, figs. 1949—50. 



Anomia — — Anton, Archiv f. Naturgesch., Ill .lalirg. 1 Bd., 1837, p. 285, No. 13. 



— œnigmalica, — Reeve, Couchol. icon., XI, 1859, Anomia, Sp. 37. 



— — — Gray, Proc. Zool. Soc. London, XVII, 1849, p. 118. 



— _ _ _ Catal. Biv. Moll. Brit. Mus., I, 1850, p. 20. 



— — — MoRLET, Journ. de Conchyl., vol. 37, 1889, p. 160. 



Aenigma — — G. C. Bourne, Quart. Journ. of Microscop. Science, No. 202. 1907. pp. 



253—95, pi. 15—17. 



— rosenm, Ghay, Mautini u. Chemnitz, Conchyl. Cabin., VII, 1. ."^btli , p. 02, pi. 7, figs. 1 — 7. 



— rcticniatum, Koch, Martini u. Chemnitz, Concliyl. Cabin., VII, 1. Abtli., p. 62, pi. 7, fig. 8. 



— convexam, _ _ . — _ — — p. 63, pi. 7, figs. 9 — 12. 



— corruijatum, — — - — — — — p. 63, pi. 7, figs. 13 — 15. 



"Palmiers d'eau à Kanipot (o: Kampot) Golfe de Slam" (L. Morlet). 

 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 ])laccnia, Linné, Systema Naturae, ed. X, 1758, p. 703, No. 205, ed. XII, p. 1154, No. 241. Mus. 



Ludov. Ulricæ, 1764, p. 536, No. 126. 

 Placuna — — Lamarck, Hist. nat. d. anira. s. vert., VI, 1 p. 1819, p. 224, No. 3, éd. 2, VII, p. 



270, No. 3. 



— — — Encyclop. method., pi. 173. 



— — — Martini u. Chemnitz, Concliyl. Cabin., VII, 1. Abth., p. 66, pi. 5, fig. 3. 



— — — Reeve, Conchol. icon., XVIII, Placuna, Sp. 3. 



— — — P. Fischer, Catalogue d. Moll, de I'lndo-Chine, p. 208. 



— — — HoRNELL, Rep. Ceylon Mar. Biolog. Laboratory, I, p. 2. 1906, p. 41. 

 Placenta urbicularis, Binzius, Diss. sist. nova testaceorum genera. Lund, 1788, p. 15. 



— — — Melvili, and Standen, Proc. Zool. Soc. London, 1906, p. 793. 



Off Koh Kam, 10 fathoms, gravel ('/:!). S. of Koh Samit, 20 fathoms, mud (^/a). 

 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 grèves du golfe de Siam" (Morlet). 



14' 



