134 SAXICAVA. 



9. siMiLis, f. 13, Deshayes. — Ehomboidea, subcompressa, 

 radiatim striata, ad angulum subserrata ; postice lata, trim- 

 cata, antice angustiuscula, umbonibus fere terminalibus. — A 

 little like S. arctica in form, but depressed, externally 

 rayed, partly serrated at the ridge, narrower in front, with 

 the umboes nearly terminal. 



10. PHOLADis, f. 5, Lamarck. — Elongata, concentrice ru- 

 gata, postice rotunde angulata, ventricosa, medio depressa, 



-antice rotunde producta; margine dorsali rectiusculo, margine 

 postico oblique truncate. — Longer and more ventricose than 

 S. arctica, and much less angular ; wrinkled concentrically. 



11. Petitii, f. 8, Deshayes. — Subtortua, postice oblique 

 inflata, ad angulum concentrice rugata, margine dorsali ad 

 terminum elevato, margine ventrali sursum acclivi ; medio 

 depresso ; antice inflato angustato ad terminum producto, 

 rotundo. — Rather tortuous in form, narrow and depressed in 

 front, inflated, wrinkled, and turned upwards at the back. 



12. SULCATA, f. 9, Deshayes. — Lata, subcuneiformis, recta, 

 rugis magnis concentricis undata ; latere antico producto, 

 rotundo, latere postico lato, ad angulum inflatum, ad termi- 

 num oblique truncate ; margine dorsali recto. — A rather large 

 species with rather large wrinkles, inflated at the angular part 

 of the posterior side. It is deeper from apex to ventral 

 margin than any excepting the two following. 



13. Angasii, f. 14, A. Adams. — Magna, irregulariter rhom- 

 boidea, alta, crassa, insequivalvis, flavido-rabescens, Isevi, sub- 

 tabulata ; latere antico truncate declivi, umbonibus magnis, 

 terminalibus ; latere postico obtuse angulato, margine ven- 

 trali acclivi. — Large, irregularly rhomboidal, deep, thick. 



14. FLACCIDA, f. 10, Gould. — Parva, tenuis, pallida, subqua- 

 drata, depressa, alba ; antice brevi, medio depressa, postice 

 quadratim rotundata. — This rather flat square species is of a" 

 pale colour, and in outline more nearly square than any of 

 the others. 



