59 155 



S. of Koh Chuen, 30 fathoms, shells ('/j). From Koh Chuen to Koh Chang, 

 15 fathoms, mud ('/s). S. of Koh Biciang, 9 fathoms, shells {^h). E. of Koh Mak, 

 20 fathoms, mud {^l-i). Between Koh Kut and Koh Kahdal, 10 fathoms, shells ('1/2). 

 W. of Koh Kut, 15 fathoms, mud C'/s). 



I.ong. 7—25 mm., alt. 8—26 mm. (1 specimen long. 22 mm., alt. 25 mm.). 



Distribution: — Philippines. 



I am relying upon Ed. v. Martens's identification, in referring these forms to 

 P. rugosus, Sow. ; as may be seen from my figures, the forms in question are very 

 ditferent from those of Sowkkby (Ri:kve). In my specimens, the intercostal parts 

 are not always smooth, but are often irregularly striated. Edg. Smith considers 

 P. rugosus, Sow., to belong to a series of forms which will probably prove to be 

 varieties of P. senntorius, Ch. Young specimens are in many cases difficult to 

 distinguish from the young of P. senatorius, Ch. 



Pecten Singaporinus, Sow. 



Peclen Singaporinus, Sowemuy, Thesaurus Conch., I, p. 74, pi. 13, fig. 55; pi. 14, fig. 71. 



— — — Reeve, Conchol. icon., VIII, Pecten, Sp. 74. 



— - — Martini u. Chemnitz, Conchyl. Cabin., VII, 2 Abth.. p. 94, pi. '25, figs. 2-4. 



— — — P. Fischer, Catalogue d. Mull, de I'lndo-Chine, p. 2U!). 



The coast of Lem Ngob (^/a). 



Long. 28 — 48 mm., alt. 25—51 mm. 



Distribution:— Singapore, Madras, Gulf of Manaar, Bombay, Gulf of Aden. 

 — Annam, Hong-kong, Port Curtis (East Australia). 



Edg. A. Smith ' considers P. pica, Reeve (from New Zealand), and P. Cumingii, 

 Reeve (from Moreton Bay), to be identical with the present species. Pilsbrv,- has 

 described from Japan an allied form, with fewer ribs, under the name of P. Awayïensis. 



Pecten cretatus, Reeve. 



Pecten cretatus, Reeve, Conchol. icon., VIII, lS5:i, Pecten, Sp. 129. 



— — — Martini u. Chemnitz, Conchyl. Cabin., VII, 2 Abth., p. 172, pi. 47, figs. 8— 9. 



North of Koh Kahdat, 4—5 fathoms, coarse sand ('/a). Between Koh Kut and 

 Koh Kahdat, 10 fathoms, shells ('/a). 



Long. 5 — 7 mm. (long. 7 mm., alt. 7 mm.). 

 Distribution unknown. 



Pecten nux, Reeve. 



Pecten nux, Reeve, Conchol. icon., VIII, 1853, Sp. 143 (see Sp. 149). 



N. of Koh Kahdat, 4 — 5 fathoms, coarse sand (Va). 

 Long. 7 mm., alt. 7 mm. 



' Report on the zoolog, collect, made during the voyage of H. M. S. "Alert." Loud. 1884, p. 115. 

 - Proc. Acad. Nat. Hist. Philadelphia, 1905, p. 121. 



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