488 



9. Pholas CANDIDA (pi. ciii. f. 21, 22, 23), Linn. Syst. Nat. 



110.1111. 



Ph. testa tenui, gradatim aperta, elongata, postice subatteuuata, 

 antice subrotundata ; costis evaniclis, ad extremitatem anticani 

 acute imbricatis ; lamina dorsali parva, elongata. 



Thin, gradually opening at the ventral margin, rounded at the 

 anterior extremity, attenuated posteriorly ; ribs faint, excepting at 

 the anterior part of the shell, where they are sharply imbricated. 



Britain. 



10. Pholas pragilis (pi. cviii. f. 92, 93), Bowerhy, jimr., 

 Pro. Zool. Soc, 1849. 



Ph. testa aperta, elongata, antice emarginata, angulari ; costis 

 radiatis et lineis coucentricis cancellata ; ad marginem dorsalem 

 reflexa; lamina dorsali angusta, arcuata. 



Eesembling Ph. parva, but much narrower, and with the um- 

 bones placed much nearer the anterior extremity. 



Collected by Mr. Cuming in soft stone, low water ; Bassy, Isle 

 of Samar, Philippines. 



11. Pholas AusTRALASiiE (pi. cvi. f. 73), Grai/, MS. Brit. 

 Museum. 



Ph. testa gradatim aperta, elongata, antice subrotundata; um- 

 bonibus prope extremitatem anticam positis ; costis distantibus, 

 obtuse imbricatis, omnino radiata; ad marginem dorsalem, ante 

 umbones, area plana; lamina dorsali una, breviuscula (?). 



Much resembling our British PJi. Candida, but a larger and 

 stronger shell, with the ribs mucli more obtusely imbricated, and 

 the umbones nearer to the anterior extremity. I have not seen 

 the dorsal sliield, but should imagine it to be much shorter in pro- 

 portion than that of Ph. Candida. 



Abundant in Australia. 



12. Pholas truncata (pi. civ. f. 29, 30), Say, American 

 Journal of Science, vol.ii. p. 321. 



Ph. testa subcylindrica, antice angulatim aperta, ad extremi- 

 tatem angulatfi, postice ad extremitatem quadrata; lineis elevatis, 

 concentricis, radiatim imbricatis, ornata ; postice laevigata ; lamina 

 dorsali elongata, arcuata, postice subquadrata. 



This shell is remarkable for its cylindrical and truncated form. 

 The radiating ribs are only seen by the imbrications, or flutings, 

 on the concentric ridges. 



