59 155 
S. of Koh Chuen, 30 fathoms, shells (‘/2). From Koh Chuen to Koh Chang, 
15 fathoms, mud (*/2). S. of Koh Bidang, 9 fathoms, shells (*/:). E. of Koh Mak, 
20 fathoms, mud (2/2). Between Koh Kut and Koh Kahdat, 10 fathoms, shells (1/2). 
W. of Koh Kut, 15 fathoms, mud (°/2). 
Long. 7—25 mm., alt. 8—26 mm. (1 specimen long. 22 mm., alt. 25 mm.). 
Distribution:— Philippines. 
I am relying upon Ep. v. Marrens’s identification, in referring these forms to 
P. rugosus, Sow.; as may be seen from my figures, the forms in question are very 
different from those of Sowrrsy (REEVE). In my specimens, the intercostal parts 
are not always smooth, but are often irregularly striated. Epc. Smirn considers 
P. rugosus, Sow., to belong to a series of forms which will probably prove to be 
varieties of P. senatorius, Ch. Young specimens are in many cases difficult to 
distinguish from the young of P. senatorius, Ch. 
Pecten Singaporinus, Sow. 
Pecten Singaporinus, SowErsy, Thesaurus Conch., I, p. 74, pl. 13, fig. 55; pl. 14, fig. 71. 
— — — ReEEveE, Conchol. icon., VIII, Pecten, Sp. 74. 
= == — Martini u. CHEMNITZ, Conchyl. Cabin., VII, 2 Abth.. p. 94, pl. 25, figs. 2—4. 
— -- — P. Fiscuer, Catalogue d. Moll. de l’Indo-Chine, p. 209. 
The coast of Lem Ngob (*/:). 
Long. 23—48 mm., alt. 25—51 mm. 
Distribution: — Singapore, Madras, Gulf of Manaar, Bombay, Gulf of Aden. 
— Annam, Hong-kong, Port Curtis (East Australia). 
Epc. A. Smiru! considers P. pica, Reeve (from New Zealand), and P. Cumingii, 
Reeve (from Moreton Bay), to be identical with the present species. Pitspry,* has 
described from Japan an allied form, with fewer ribs, under the name of P. Awajiensis. 
Pecten cretatus, Reeve. 
Pecten cretalus, Reeve, Conchol. icon., VIII, 1853, Pecten, Sp. 129. 
—_— = — Martini u. Cuemnirz, Conchyl. Cabin., VII, 2 Abth., p.172, pl. 47, figs. 8—9. 
North of Koh Kahdat, 4—5 fathoms, coarse sand (‘/2). Between Koh Kut and 
Koh Kahdat, 10 fathoms, shells (1/2). 
Long. 5—7 mm. (long. 7 mm., all. 7 mm.). 
Distribution unknown. 
Pecten nux, Reeve. 
Peclen nux, REEVE, Conchol, icon., VIII, 1853, Sp. 143 (see Sp. 149). 
N. of Koh Kahdat, 4—5 fathoms, coarse sand ('/2). 
Long. 7 mm., alt. 7 mm. 
' Report on the zoolog. collect. made during the voyage of H. M. S. “Alert.” Lond. 1884, p, 115. 
* Proc. Acad. Nat. Hist. Philadelphia, 1905, p. 121. 
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