PART II. WACROTRACHIA. SAXICA VID.E. 375 



€leidoth(xrus Stuchbury. Shell resembling Chama, but 

 somewhat pearly ; liinge with an " internal^ testa- 

 ceous, curved appendage," inserted in a depression 

 within each of the bosses. 



C. chamoides. Sow. Man. f. 75. 



D'lceras Lam. Somewhat resembling Isocardia ; but 

 the bosses are excessively produced and turned dif- 

 ferent ways. Fossil only. 



D. arietinum. Sow. Gen. f. 1. 

 Myochama * Stuchbury. Shell irregular, smooth, at- 

 tached by the lower valve ; umbones central ; cardinal 

 teeth small, '-, between which is an internal shelly 

 appendage, attached to a horny cartilage. 



M. anomiodes. Sow. Man. f. 73. 



Cardita t Lam. Shell 

 free, cardiform, or 

 sub-transverse, rib- 

 bed ; cardinal teeth 

 ^ or ^, lateral J- ; re- 

 presenting Cardium. 

 {fig. 121.) 



C. sulcatus. Sow. Gen. f. 3. imbricatus. lb. f. 4. 

 calyculatus. lb. f. 1, 2. oblonga. lb. 



Family SAXICAVID^. 



Animal perforating ; shell often irregular ; lateral teeth 



none j cardinal teeth variable or obsolete. 



Saxicava Lam. Shell transversely oval, irregular, 

 gaping at one or both ends ; ligament external ; teeth 

 obsolete. (%. 122. a, e.) 



S. rugosa. Sow. Gen. f. 1 — 4. 



Petricola Lam. Shell transversely oval or oblong ; the 



valves gaping ; cardinal teeth variable, but always 



present ; lateral teeth none {fig. 122. 6, c, d.) 



P. dactylus. Sow. Gen. f. 3. ochrolcuca. lb. f. 4. (b.) 



* Affinities uncertain. 



f Including Vencricnrdia .and Cypricardia Lam. {fig. 121.), the latter 

 seems an aberrant Cardita, passing into Coralliophaga. 



B B 4 



