MAZATLAN BIVALVES 81 



FAMILY ASTAETID^, 



Cyprinidse, Forbes, Woodw. This name has been previously 

 appropriated for a family of Fishes. Gray divides it into 

 four families, Carditidse, Astartidse, Crassatellidse, and Glos- 

 sidse (Isocardia, Lam.) 



GENUS CIECE, Sckum. 



Cytherea (pars) Lam. This genus is ranked with the Veneridse 

 by Gray fy Desk., with As tart e and Cyprina by Forbes and 

 Woodw. 



-f ' 114. ClKCE MAKGAEITA, ft. S. 



C. t. minima, subovali, incequilaterali, umbonibus appressis, 

 subrugosis, concentrice liratd, liris acutis, area lunuldque 

 indistinctis, ligament o celato : parte anteriori dilatd, 

 posteriori parvd ; dente laierali antic o maximo, alterd in 

 valvd in cardinalem confluente ; postico longo, exili : cardinali- 

 bus 2-3 : impressionibus muscularibus, sub&qualibus, lined pallii 

 d margine remotd ; albd flavescente, dentibus pwrp&reis ; epi- 

 dermide tenui. 



This genus abounds in the Red Sea, Australia and the East 

 Indies generally. It has not been described from the American 

 coast. I have several species -in a collection sent from the U. S. 

 as from S. America ; but as nearly all are identical with Aus- 

 tralian species, the locality is probably erroneous. The charm- 

 ing little C. margarita however establishes its claim to a place 

 in the genus, by its appressed, somewhat rugose umbos, semi- 

 internal ligament, large anterior tooth, and the pallial line 

 which, though generally indistinct, is certainly not sinuated. 

 It is oval, with very delicate, rather sharp concentric lines, 

 covered with a thin epidermis ; sometimes subdiaphanous, 

 sometimes opaque and yellowisli inside, with a purple tinge 

 on the teeth. It may be the young of a larger species not yet 

 discovered, but as about a score of specimens were found fresh, 

 nearly of the same size, and with the rugose portion of the 

 umbos clearly distinguished, it may not improbably be adult. 

 Long. "05, lat. '07, alt. '03. 

 Hab. Mazatlan ; on Spondylus Lamarckii, very rare ; L'pool 



Col. 



Tablet 412 contains 1 pair closed ; 2 do. open, (the largest 

 and smallest,) and 1 yellowish valve. 



