492 



Differing from Ph. Califomica in the dorsal side of the anterior 

 part, which is finely striated in both directions ; in the epider- 

 midal laminae, which are beautifully serrated ; in the integumental 

 covering of the dorsal edge, which is divided into four parts, of 

 which the posterior pair are long, and one overlapping the other ; 

 and in the absence of integumental lamina; on the ventral margin. 



Collected by Capt. Ince, R.N., in coral rock at Raine's Island, 

 Torres Straits. 



22. Pholas acuminata (pi. cv. f. 48, 49, 50), Sowerby, Pro. 

 Zool. Soc, 1834. 



Ph. testa, subpyriformi, clausa, ventricosa ; in partes fares ob- 

 lique divisa ; parte antica prope marginem ventralem laevigata, in 

 medio et ad dorsum minute radiatim scabra; parte media late 

 plana, epidermide crassa induta; parte postica acute angulata, 

 attenuata, fascia serrata marginata, epidermide laminis angulatis 

 induta ; margine ventrali integumento elongate, integro ; margine 

 dorsali integumento ad umbones magno, subquadrato, postice 

 altero elongato, prope umbones rotundato ; marginibus ventralibus 

 valvarum unidentatis. 



Shell pyriform, rounded anteriorly, and tapering towards the 

 end. Surface of the valves divided obliquely by serrated groves 

 into three parts ; the anterior part divided again longitudinally; 

 the ventral side smooth, horny ; the dorsal side finely ribbed in 

 both directions, the middle part plain, with a thick epidermis ; 

 in the posterior part, the epidermis is raised in smooth laminae, 

 corresponding in shape with the attenuated and acutely angulated 

 termination. The external integuments are, one narrow, folding 

 along the ventral margin ; one large, subquadrate upon, and ante- 

 rior to, the umbones ; the other, adjoining by a rounded lobe, 

 and tapering off to the posterior end of the dorsal edge : these 

 are not quite divided by a central line. 



In limestone rocks at low water, at Panama. Cuming. 



23. Pholas quadkizonalis (pi. cviii. f. 88, 89), Spengler. 



Ph. testa clausa, subcylindrica, ventricosa, in partes tres transver- 

 sales divisa ; parte antica prope marginem laevigata, in medio et ad 

 dorsum minute striata ; parte mediana plana ; parte postica epider- 

 mide laminis serratis induta ; margine dorsali integumento subtes- 

 taceo in partes quatuor diviso, quarum duas anticas breviusculas, 

 duas posticas elongatas, trilobatas. 



Resembling Ph. Incii, but much smaller, and more finely 



