173 269 
shell and curve over towards the front. In the right valve there is one cardinal 
tooth, which fits into a corresponding pit in the left valve, behind which is a stout 
process or denticle supporting the ligament. The interior of the valves, like the 
exterior, is clear-white in colour. 
Long. 9°5 mm., alt. 5 mm., crass. 5°5 mm. 
Between Koh Kut and Koh Kahdat, 10 fathoms, shells (7/2). Koh Kahdat (*/2). 
South of Koh Kahdat, 8—10 fathoms, mud (*/2). 
This small characteristic species, which in form recalls an Arca (Barbatia), stands 
nearest Corbula tenuis, Sow., from which it differs, however, in many points. The 
specimens which I have before me are not well-preserved, no trace of epidermis 
is seen upon any of them; also, I cannot, unfortunately, state anything about the 
reciprocal size of the two valves. But in all probability, the difference in size is 
not very great, as both right and left valves are at hand, but of different individuals. 
Corbula rugifera, A. Ad. (Smith). 
Corbula rugifera, A. AbAMs, MS. in Coll. Cuming. Brit. Mus. 
— Epc. Smiru, Proc. Malacolog. Soc. London, V, 1903, p. 399, No. 373, pl. 15, figs. 
9—10. 
— — H. Apams, MEtvitt and SranvENn, Proc. Zool. Soc. London, 1906, p. 843. 
Koh Kram, 20 fathoms (*/2). 
Long. 3:55—8 mm. 
Distribution: — Singapore (Sy. Gap, Zoolog. Mus. Copenhagen). Karachi 
(Hindustan, Metvitt). Umkomaas (South Africa, BuRNUP). 
After Epc. Smiru in 1903 had published the description of the present charac- 
teristic species from South Africa, MELviLt, in 1906, recorded that it had been 
taken at Karachi. Its occurrence at Singapore and in the Gulf of Siam, renders 
it probable that later on it may also be found in the interjacent waters. 
Corbula Taheitensis, Lam. 
Corbula taitensis, LAMARcK, Hist. nat. d. anim. s. vert., V, 1818, p. 496, No. 5. 
— Taitensis, - éd. 2, VI, p. 139, No. 5. 
—- Taheitensis, — Reeve, Conchol. icon., Il, Corbula, Sp. 15. 
— Tahitensis, = — Han ey, Catal. of rec. biv. shells, p. 46, pl. 12, fig. 30. 
— Taitensis, — HipaLco, Fauna malacol. de 1. isl. Filip., II, 1903, p.31, No. 59. 
Koh Chuen, 30 fathoms ('/2). Between Koh Mesan and Koh Chuen, 25—38 
fathoms, stones and shells (1 + 2/2). North end of Koh Chang, 12 fathoms, old 
coral blocks ('/2). 
Long. 6—8 mm. 
Distribution — Aden. — Philippines, New Guinea, Torres Str., Tahiti, 
Funafuti Atoll (HepLey). 
