488 



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

 no. 1111. 



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

 antice subrotundata ; costis evanidis, ad extremitatem anticam 

 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 fragilis (pi. cviii. f. 92, 93), Sowerby, junr., 

 Pro. Zool. Soc, 1849. 



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

 radiatis et lineis concentricis cancellata; ad marginem dorsalem 

 reflexa; lamina dorsali angusta, arcuata. 



Resembling 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 Australasia (pi. cvi. f. 73), Gray, MS. Brit. 

 Museum. 



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

 bonibus prope extremitatem anticam positis ; costis distantibus, 

 obtuse imbricatis, omninb radiata; ad marginem dorsalem, ante 

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



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

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

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

 the dorsal shield, 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 subcylindricfi, antice angulatim aperta, ad extremi- 

 tatem angulata, 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 flirtings, 

 on the concentric ridges. 



