366 



Found by Mr. Cuming attached to Mytili, at a depth of six 

 fathoms, off Conception, Cliili. 



3. Oebicula tenuis (pi. Ixxiii. f. 4, 5.) nobis. 



Testa Isevi, tenui, apice ad marginem propinquo. 



Shell smooth, thin, apex of the upper valve near the posterior 

 margin ; disk of adhesion obtusely triangular^ close to the liinder 

 edge ; perforation linear. 



4. Oebicula Cumingii (pi. Ixxiii. f. 6.) Brod. Zool. Proc. 

 1833. p. 124. 



Testa snbconica, suborbiculari, crassiuscula, striis ab apice 

 radiantibus niimerosis, lineis incrementi elevatis decussantibus, 

 epidermide paUide fusca. 



Shell nearly orbicular, subcorneal, rather thick, with numerous 

 strise radiating from the subcentral apex, and decussated by the 

 elevated lines of growth ; epidermis of a pale brown colour. 



round by H. Cuming, at Payta, St. Elena and Panama. 



5. Oebicula strigata (pi. Ixxiii. f. 7.) Brod, Zoo\. Trans, 

 vol. i. pt. 2. pl. xxiii. f. 1. 



Testa crassiuscula, subrotunda, substriata, radiatim castaneo- 

 strigata ; epidermide tenui fusca. 



SheU rather thick, nearly orbicular, slightly striated, radiately 

 streaked with chesnut colour, epidermis thin, pale brown. 



Island of Caiia, Guatemala, Malacca, and Corrigedor ; H. Cimiing. 



6. Oebicula steiata (pl. Ixxiii. f. 8.) Sow. Trans, of Linn. 

 Soc. vol. xiii. 



Testae valvula superiore striis elevatis plurimis, ex vertice ad 

 marginem decurrentibus. 



SheU rather irregularly orbicular, thickish, apex nearly central ; 

 upper valve with numerous elevated striae from the apex to the 

 margin. 



This is the species which Lamarck has elevated to the rank of 

 a genus (named Biscina), from not rightly knowing his own pre- 

 viously established genus Orbicula. 



Locality unknown ; found in ballast used to mend roads near 

 London. 



CRANIA. 



Testa iasequivalvis, aequilatera, (subirregularis) rotundato-sub- 



