MAZATLAN BIVALVES 81 
Fimity ASTARTID ZA, 
Cyprinide, Forbes, Woodw. This name has been previously 
appropriated for a family of Fishes. Gray divides it into 
four families, Carditide, Astartide, Crassatellide, and Glos- 
sidee{(Isocardia, Lam.) 
Genus CIRCE, Schum. 
Cytherea (pars) Lam.—This genus is ranked with the Veneride 
by Gray & Desh., with Astarte and Cyprina by Forbes and 
Woodw. 
114. CIRCE MARGARITA, 7. s. 
C. t. minima, subovali, inequilaterali, umbonibus appressis, 
subrugosis, concentrice liratéd, liris acutis, ared lunuldque 
indistinctis, ligamento celato: parte antertori dilata, 
posteriort parva; dente laterali antico maximo, alterd in 
valva in cardinalem confluente ; postico longo, exili: cardinali- 
bus 2-3: impressionibus muscularibus, subaqualibus, lined pallia 
ad margine remota ; albd flavescente, dentibus purpureis ; epti- 
dermide tenut. 
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 yellowish 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, alé. °03. 
Hab.—Mazatlan ; on Spondylus Lamarckii, very rare; LZ’ pool 
Col. - 
Tablet 412 contains 1 pair closed; 2 do. open, (the largest 
and smallest,) and 1 yellowish valve. 
