125 221 
Mactra cuneata, Carmnrrz, Weinkaurr in Martini u. CHemnirz, Conchyl. Cabin., XI Bd., 2 Abth., p. 13, 
No. 10, pl. 4, figs. 3—4. 
— purpurea, SeENGLER, Skrivter af Naturhistorie-Selskabet, V Bd., 2 Hefte, 1802, p. 111, No. 17. 
_ corbiculoides, DesHayes, Proc. Zool. Soc. London, XXII, 1854, p. 62, No. 4. 
= Reeve, Conchol. icon., VII, Mactra, Sp. 98. 
— WeINKAuFF in Martini u. Cuemnitz, Conchyl. Cabin., XI Bd., 2 Abth., 
p. 91, No. 97, pl. 31, fig. 3. 
The strand off the Mangrove at the station on Koh Chang, shallow water (3). 
The strand of Koh Kahdat (°/2). 
Long. 4—15 mm. 
Distribution: — Nicobars, Ceylon, and Gulf of Manaar. 
The small individuals from the Gulf of Siam agree fairly well with REEVE’s 
cuneata, which is probably founded on not full-grown individuals, at any rate 
SPENGLER’S original specimens of M. purpurea are considerably larger (long. 31 mm., 
alt. 27°5 mm., crass. 18 mm.) and are thick-valved. I cannot find any difference 
between the latter and Desuayes’s corbiculoides, which, judging from the figure and 
description, agrees in all points with it; therefore, I have not hesitated in giving 
them as synonyms. Setting aside the outline, the following features are charac- 
teristic of M. cuneata, Ch.:—- the intense dark-lilac colour of the interior of the 
valves (the lateral teeth are pale), the pale lilac and ash-gray colour of the exterior 
of the valves, and the beautiful regular striation of the lunule and area. Besides 
this typical form there are also individuals which are entirely white, without a 
trace of colour (CHEMNITZ has already mentioned such specimens), several specimens 
of this variety were taken at Koh Kahdat. I entirely agree with WEInKAUFF when 
he writes (loc. cit. p. 29) that M. Jurida, Phil., is very near to M. corbiculoides, Desh. ; 
I think that lurida can scarcely be separated from M. cuneata, Ch. (= corbiculoides, 
Desh.), as a good species. 
Mactra (Trigonella) Luzonica, Desh. 
Mactra Luzonica, Desuayes, Proc. Zool. Soc. London, 1854, p. 64, No. 12. 
— — — Reeve, Conchol. icon., VIIl, Mactra, Sp. 81. 
— — — WEINKAUFF in Martini u. CHEMNITZ, Conchyl. Cabin., XI Bd., 2 Abth., 1884, 
p. 49, No. 48, pl. 17, figs. 1—2. 
— — — Hipaueo, Fauna malacol. de |. isl. Filipinas, Il, 1903, p. 50, No. 102. 
Koh Kahdat ('/2). 
Long. 14 mm., alt. 95 mm. 
Distribution: — Arakan Coast (BLANFORD), Calcutta (Lady HerscuEL), Madras 
(HENDERSON), Ceylon (HERDMAN), Bombay (MELviILL & ABERCROMBIE), the coast of 
Continental India (from Karachi to Panjim, Metvitt & STanpEN). — Philippines 
(CUMING). 
Though the small valve which is at hand is somewhat worn, | have no doubt 
as to the correctness of the determination. G. F. AnGas (Proc. Zool. Soc. London, 
1867, p.916. — J.C. Cox, Exchange List of Land and Marine Shells from Australia, 
