52 



-MAZATLAN BIVALVES 



Brazils, Ilio de Janeiro, Patagonia; "Baie Blanche, Voi/. 

 no. 130," -D'0/'J/7«y.— Mazatlan; one specimen was sent, 

 quite fresh, papered up along with the Semeles ; L'pool Col. 

 Tablet 213 contains the specimen. 



80. Mactea (Mulinia) angulata, Gray, ms. 

 Bve. Convh. Icon. pi. ix. sp. 34. 



This species is known at once from the young of M. exoleta 

 by its stout, subtrigoual growth, the shortness of the anterior 

 portion and the rather distant umbos. The epidermis is extreme- 

 ly thin, gradually passing off towards the anterior portion, as in 

 M. exoleta; but diiFers in being loose, lying in irregidar concen- 

 tric folds, fringed at the posterior angle. The hmge teeth are 

 large and prominent; lateral ones very finely shagreened. 

 The muscidar impressions are singularly close to the margin 

 of the shell; pallial sinus small, oval. .PCan this be the M. 

 donaciformis of C. B. Ad. (Pan. Shells p. 293,) as the true 

 M. donaciformis is given by Rve. as from N. Zealand.* This 

 shell seems also to have relations with M. goniata, Gray, ons. 

 (Proc. Zool. Soc. 1854, p. 70,) and with M. carinulata, Desk. 

 (Proc. Zool. Soc. 1854, p. 67: Rve. Conch. Icon. pi. 10, sp. 38), 

 both from the gulf of California. Long. 2-25. lat. S'Oo, alt. VIS. 

 Rah.—GxxU of California, Eeeve.— S. W. Mexico, P. P. C— 



Mazatlan ; a verj- few specimens were found with M. exoleta : 



IJpool Col. 



Tablet 214 contains two specimens ; one young with the 

 epidermis perfect ; the other adidt. 



Genus GNATHODON, aray. 



Guathodon, Gray, Am. Journ. of Sciewe ? 1830.— Eangia, 

 De.rmoul. Ac. Soc. Lin. de Bord. 1831.— Clathrodon, Conr. 

 Sillini. Anier. Journ. 1833. 



81. Gnathodon (Eangia) trigona, Petit. 



G. t. solidA, »uhtrigonali, alba, epidermide flavescente, pos- 

 terius rugosa, indutCt ; plus mimisve incpquilaterali, parte pos- 

 teriori angiilo ah umhonibus decurrente indistincte separatd; 

 Kmhonihujt snhcentralihus, distantibus, non spiraliter recurvis ; 



* Reeve however, under M. carinulata, sp. 38, speaks of M. donacifcrrmis as 

 from the Gulf of Cnlilbrnin. F Is it authenticated from both localities. 



