146 50 



E. of Kolî Chuen, 9 — 10 fathoms, shells (1). Koh Kahdat, 1 fathom, sand 

 (1 abnormal specimen). Koh Kram, 30 fathoms (1 specimen, alt. 11 ram.). 



Long. 19 mm., alt. 31 mm. 



Distribution; — Persian Gulf, Gulf of Aden, Red Sea, Suez, Ascension Isl. 

 (Edg. a. Smith). — Philippines, Japan, Timor, Moluccas; North-west and South 

 Australia. 



The specimen from Koh Chuen belongs to var. decurtntits, Lam., while the 

 specimens from Koh Kahdat and Koh Kram must be referred more especially to 

 M. régula, Forsk. A single valve (long. 13 mm., alt. 15 mm.) was taken between 

 Koh Kut and Koh Kahdat (in about 10 fathoms, on a shelly bottom); this must 

 undoubtedly be referred to var. deciirtatus. Lam. 



Perna vespertilio, Reeve. 



Perna vespertilio, Reeve, Conchol. icon., XI, Perna, Sp. 26. 



— — — Martini u. Chemnitz, Conchyl. Cabin., VIII, 1 Abtli., p. 37, pi. 13, fig. 2. 



Koh Kram, 30 fathoms (1/2). 



Long. 53 mm., alt. 55 mm. 



Distribution: — Philippines. 



As far as I can judge from the scanty material at my disposal, this species 

 varies exceedingly, and if a number of specimens could be obtained for comparison 

 from the same district, several forms, which are now regarded as distinct species, 

 would undoubtedly be reduced to synonyms; indeed perhaps it would be necessary 

 to refer the whole "species" to another form. 



Perna Spengleri, Chemn. 



Siliqua Spengleri, Chemnitz, Conchyl. Cabin., VII, 1784, p. 250, pi. 59, fig. 578. 

 Ostrea Legumen, Gmelin, Syst. Nat., ed. XIII, p. 3339, No. 128. 

 Perna dactylus, Valenciennes, Encycl. method., pi. 175, figs. 2—3. 



— legumen, Gmelin, Reeve, Conchol. icon., XI, Perna, Sp. 22. 



— linguaeformis, — — — Sp. 7. 



— laticostata, — — — Sp. 9. 



— candata, — — — Sp. 5. 



- Reeve, A. H. Cooke, Ann. & Mag. Nat. Hist., XVII, 5 Ser., 1886, p. 138. 



Common at Koh Chang, Koh Lom and Koh Kahdat, 1 — 12 fathoms, sand 

 and old coral blocks. 



Long. 4—12, alt. 5—26 mm. 



Distribution:— Mergui Archip., Nicobars, Red Sea, Lifu Isis., Society Isis. 



I have i-e-introduced Chemnitz's name, which, strangely enough, in spite of its 

 priority, has hitherto been disregarded. The original specimen figured by Chemnitz 

 (besides a smaller one from Spengler's collection), is in the Zoological Museum of 

 the University of Copenhagen. It is somewhat worn and deformed, but nevertheless 

 agrees entirely with Gmehn's P. legumen. The deep-blue spots at the beaks men- 

 tioned by Chemnitz, are due to the fact, that the valves of his specimen, when 



