125 221 



Mactra ciineata, Chkmnitz, Wkinkaui r in Mahtini u. Chemnitz, Coiicliyl. Cabin., XI lid., 2 Abtli., p. l.'i, 



No. 10, pi. 4, figs. 3—4. 



— puriHirea. Spkngleh, SUrivter 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., VIII, Mactra, Sp. 98. 



— — — Weinkauff in Martini u. Chemnitz, Conchyl. Cabin., XI Bd., 2 Abth., 



p. 91, No. 97, pi. 31, fig. 3. 



The strand off the Mangrove at the station on Koh Chang, shalhnv water (3). 

 The strand of Koh Kahdat ("'/i). 



Long. 4—15 mm. 



Distribution: — Nicobars, Cej'lon, 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 Ihick-valved. I cannot find any difference 

 between tlie latter and Deshayes'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, Gh.: — 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. lurida, 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. 



Maclra Luzonica, Deshayes, Proc. Zool. Soc. London, 1854, p. 64, No. 12. 



— — — Reeve, Conchol. icon., VIII, Mactra, Sp. 81. 



— — — Weinkauff in Martini u. Chemnitz, Conchyl. Cabin., XI Bd., 2 Abth., 1884, 



p. 49, No. 48, pi. 17, figs. 1-2. 



— — — Hidalgo, Fauna malacol. de I. isl. Filipinas, II, 1903, p. 50, No. 102. 



Koh Kahdat {'k). 



Long. 14 mm., alt. 95 mm. 



Distribution: — Arakan Coast (Blanford), Calcutta (Lady Herschel), Madras 

 (Henderson), Ceylon (Herdman), Bombaj' (Melvill & Abercrombie), the coast of 

 Continental India (from Karachi to Panjim, Melvill & Standen). — Philippines 

 (Cuming). 



Though the small valve which is at hand is somewhat worn, 1 have no doubt 

 as to the correctness of the determination. G. F. Angas (Proc. Zool. Soc. London, 

 1867, p. 916. — J. C. Co.x, Exchange List of Land and Marine Shells from Australia, 



