615 



9. Cytheraia eadiata (pi. cxxviii. f. 28^ 29, 30, 31), G. B. 

 Sowerbif, Zool. Proc. 1835. p. 23. 



Cyth. testa subtrigona, subsequilatera, gibbosa, pallescentc- 

 brunneo radiata et undulatim picta, Isevi, epidermide cornea 

 crassiuscula plus minus induta ; lateribus antico posticoque ven- 

 trem versus rotundatis ; margine ventrali rectiusciilo, intus Isevi. 



The ventral edge is nearly straight, and the sides somewhat 

 squared ; the broad rays of colour have undulating markings be- 

 tween them. In these respects, as well as in being rather less 

 ventricose, C. radiata differs from C. corbicula. 



Salango and Xipixapi, West Columbia ; sandy mud, five fa- 

 thoms. Cuming. 



10. Cyther^a gracilior (pi. cxxviii. f. 32), Sowerhy, jun. 



Cyth. testa alba, C. radiata simili, sed magis elongata, latere 

 postico subattenuato. 



A wliite shell, much more elongated than C. radiata, with the 

 posterior side obliquely drawn out ; an impressed line on the ante- 

 rior surface defines the lunule. 



Locality unknown. Specimen kindly furnished by Mr. Hanley. 



11. CYTHERiEA Mactroides (pi. cxxviii. f. 36), milwyn, 

 p. 173. Chemn. f. 330, 331. Lamarck, no. 27 ? 



Cyth. testa ovali-subtrigona, fasciis castaneis radiata, solida, 

 Isevi ; margine ventrali subrotunda ; lateribus breviusculis, postico 

 rotundatim subangulato ; area cardinali postica cordiformi, cas- 

 tanea ; lunula indistincta, prope umbones rubra, tum albo uni- 

 fasciata. 



Shell more evenly oval than either C. corhicula or C. radiata, 

 with the sides shorter, and the whole shell longer in proportion to 

 its height ; the chestimt rays are broader than the intermediate 

 whites ; the hinge area is reddish-brown near the umbones, with 

 a wliite broad band enclosing the brown. 



Probably from the West Indies. 



12. CYTHERiEA INTERMEDIA (pi. cxxviii. f. 35), Sowerbi/,jun. 



Cyth. testa ovali-subtrigona, alba, suba^quilatera, Ipevi, com- 

 pressa ; margine ventrali rectiusculo ; latere postico subangulato. 



A white, trigonal, rather compressed shell, neither so high nor 

 so tumid as C. radiata, and having the ventral margin more 

 straight, and the hinder side more squared, than in C. depressa. 



California. Cuming. 



