146 50 
E. of Koh Chuen, 9—10 fathoms, shells (1). Koh Kahdat, 1 fathom, sand 
(1 abnormal specimen). Koh Kram, 30 fathoms (1 specimen, alt. 11 mm.). 
Long. 19 mm., alt. 31 mm. 
Distribution: — Persian Gulf, Gulf of Aden, Red Sea, Suez, Ascension Isl. 
(Epc. A. Smirn). — Philippines, Japan, Timor, Moluccas; North-west and South 
Australia. 
The specimen from Koh Chuen belongs to var. decurtatus, Lam., while the 
specimens from Koh Kahdat and Koh Kram must be referred more especially to 
M. regula, 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. decurtatus, Lam. 
Perna vespertilio, Reeve. 
Perna vespertilio, REEVE, Conchol, icon., XI, Perna, Sp. 26. 
= = - Martini u. CHEMNITZ, Conchyl. Cabin., VIII, 1 Abth., p.37, pl. 13, fig. 2. 
Koh Kram, 30 fathoms (*/2). 
Long. 538 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, pl. 59, fig. 578. 
Ostrea Legumen, GMELIN, Syst. Nat., ed. XII, p. 3339, No. 128. 
Perna dactylus, VALENCIENNES, Encycl. méthod., pl. 175, figs. 2—3. 
—  legumen, GMELIN, REEVE, Conchol. icon., XI, Perna, Sp. 22. 
—  linguaeformis, - — — Sp. 7. 
—  laticostata, — — — Sp. 9. 
—  caudatla, — _ — 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 Isls., Society Isls. 
I have re-introduced CHEmnirz’s name, which, strangely enough, in spite of its 
priority, has hitherto been disregarded. The original specimen figured by Cuemnirz 
(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 GmELIN’s P.legumen. The deep-blue spots at the beaks men- 
tioned by Cuemnirz, are due to the fact, that the valves of his specimen, when 
