PHOLAS —Plate V. 



with a thick epidermis; posterior part acutely 

 angular, attenuated ; dorsal and ventral margins 

 covered with folded integuments ; a single dorsal 

 valve, large and rather square. 

 SowERBY. Proc. Zool. See, 1834. 



Hah. Panama. In limestone rocks at low water. 

 Differing in form from Pholas calva, being narrower 

 and more aciuninated, with a smaller, rather square 

 dorsal shield. 



Species 20. (Mus. Cum. in Brit.) 

 Pholas calva. Plio. testa clausd, latd, suhpyiiformi, 

 antice rotunclA : medio piano, epiderniidi crasm 



indutd ; antice attenuatd, laminatd, ad terminum 

 suhacuminata, maryinibus dorsalihus ventrali- 

 husque integumentibus plicalis cwlatis ; lamina 

 dorsali late expansd, lohatd. 



The skull Pholas. Shell closed, wide, suhpyriform, 

 anteriorly rounded ; middle flat, covered with a 

 thick epidermis ; anteriorly attenuated, laminated, 

 subacuminated at the end ; dorsal and ventral 

 margins covered with folded integuments ; dorsal 

 lamina broadly expanded lobed. 



SoWERBV. Proc. Zool. Soc, 1834. 



Hah. Panama Bay. In hard stone, at low water. A 

 broad, somewhat irregularly-lobed dorsal shield is 

 expanded over a large part of the dorsal margin 

 and part of the rounded head. 



