Dr. J. E. Gray on some Families of Bivalve Shells. 43 



interior lateral teeth erect, hinder very small, often obliterated 

 in adult shells. L. elliptica. 



14. Zenatia. Lutraria sp., Quoy. Shell oblong, elongate, 

 compressed ; umbo anterior, submarginal, hinder gape large ; 

 cardinal teeth distinct, lateral teeth none. Z. zelandica. 



15. Resania. Shell oblong, rounded in front, tapering be- V)»V\r 

 hind, strengthened by two broad raised diverging ribs within; | * y 

 umbo central, hinder gape moderate ; cardinal teeth distinct ; , -^ ■ ^ 

 anterior lateral tooth very small, close to the cartilage-pit, 

 posterior none. 



R. lanceolata. Shell oblong, lanceolate, compressed, tapering 

 behind, white. N.Zealand. yiiT 



16. Cypricea, Gray, P. Z. S. 1847, n. 1«5-. Lutraria **, Gray, 

 Mag. N. H. i. iW'. Shell oblong, marked with an oblique pos- 

 terior ridge, largely gaping and reflexed behind ; lateral teeth di- 

 stinct; anterior oblique, near the small cartilage -pit. C.recurva. ^ 



17. Raeta, Lutraria ***, Gray, Mag. N. H. i. 37^. Shell ^ 

 cordate, ventricose, thin, slightly produced and rather gaping 

 behind, hinder slope keeled, na^rrow ; cardinal teeth strong ; 

 hinder lateral tooth small, distinct. R. campechensis. 



c. Abnormal; ligament marginal near cartilage ; cardinal tooth of 

 left valve broad, triangular, nicked. 



18. Coecella. Shell oblong, subequilateral ; lateral teeth very 

 small, close to the cardinal tooth; cartilage-pit produced into 

 the cavity of the shell. 



C. Horsfieldii. Madras and China. Perhaps the type of a new 

 family. 



The genus Pythina of Hinds (Zool. Sulphur, 71. 1. 19. f. 8, 9), 

 which that author has referred to Mactrada, evidently belongs 

 to LasiadcB, ^.nd is very nearly allied to Kellia. 



Fam. 9. Anatinellad^e. 



Shell oblong, rather gaping behind, equivalve, equilateral; 

 umbo central, white ; covered with a thin smooth periostraca. 

 Ligament thin; cartilage internal, in an oblong nari'ow pit, 

 projecting into the cavity of the shell, nearly at right angles 

 with the cardinal edge. Cardinal teeth in the right valve two, 

 diverging, slightly raised ; of the left valve single, triangular, 

 rather bifid ; lateral teeth none. Siphonal inflection none ; an- 

 terior scar elongate, slender, marginal, hinder oblong, trian- 

 gular. 



The Anatinelladce are like a roundish Lutraria without any 

 lateral teeth, but the cardinal teeth are less developed, and there 



