MAZATLAN BIVALVES 43 



anterior side much elongated. Long. 1"52, (ad sinum 1"37,) 



lat. 2*28, alt. '9, (ad sinum -78.) 



Hdb. — Mazatlan ; extremely rare ; L'pool Col. 



Tablet 137 contains the only specimen I found : Mr. White- 

 head of Liverpool found another. 



Genus DONAX, Unn.* 



71. DoNAX CAEINATUS, Sanl. 



Proc. Zool. Soc, 1843, p. o.—Bve. Conch. Icon. pi. 2, sp. 11.— 



Wood's Su/ppl. pi. 14, f. 28. 



Shell with a blunt keel, and posterior area covered with 

 slightly expressed striae which are scarcely rugose here and 

 there. Epidermis very thin, deciduous except round the mar- 

 gin. Ventral margin almost always regularly excurved. The 

 purple colour generally predominates in this, as the chesnut 

 in D. culminatus. Form and markings very constant, except, 

 as usual, in the proportion of length and breadth. Long. '93, 

 Int. 1-62, alt. -63. 

 Hah.—^an Bias, Gulf of California, Eeeve.— Tumaco, Hinds, 



B. M. — Mazatlan ; rare ; L'pool Col. 



Tablet 138 contains 2 specimens in the normal state, and one 

 with two remarkable laminae in the interior of one valve, near 

 the posterior adductor. 



72. DOXAX CULMINATUS, In. s. 



D. carinatus, var : Hani. ms. teste Cuming. 



D. t. "D. carinato" simili, sed carina multo acutiore,'producta. 

 margine ventraU scepe prope carinam paiilum inciirvato ; niten- 

 tiore ; stinis radiantibus ohsoletis et crenulatione interna convent- 

 ente erebrioribus ; areA posticd striis radiantibus creberrimis 

 valdeextantibus, granosis, granis versus inarginem rugosis ; 

 castaneo-purpureo. 



I had passed this shell over as the young of D. carinatus, till I 

 obtained a number of large valves with other West Coast shells, 

 which at once displayed the remarkable characters of the 

 posterior area, the sharp ridge, and the very granular crowded 

 striae. Having examined more than 60 specimens of D. carin- 



• The specific termination being ^ven as feminine in P. Z. S., S. M. Cat. 

 B'Orb. Moll., Rie. Conch. Icon., Jay's Cat. &c., it is desirable to remember that 

 Donax is masculine both in Latin and Greek : (v. Lex.) In quoting, the termin- 

 ations are altered accordingly. 



