EXOTIC CONCHOLOGY. 29 



clearly distinguish it.) The ligament also is connate and entirely covered by a 

 prolongation of the testaceous matter of the valves, the bosses small, and the shell 

 itself ovate-trigonal and depressed. The cardinal teeth are very peculiar ; they are 

 compressed and crenated like those of mysca, but the inner one is generally the 

 largest, and the direction of the grove which separates them is either perpendicular, 

 or diverges from the anterior margin of the shell. The colour is dark olive, and 

 the inside pearly. Inhabits Lake Champlain, St. George, &c. in North America. 

 Extreme breadth three inches and a half. 



Sub-Family— HYRIAN^. 



Bosses longitudinally furrowed : cardinal teeth long, compressed, placed on one side of the 



bosses ; hinge margin winged. 

 Genus — Hyria. Hinge margin straight; both extremities elevated and winged : cardinal 



teeth very long, and resembling lateral teeth. 



HYRIA ELONGATA. 



Plate XXIV. 



Testa elongata, oblongo-trigona, fusca, margiue superiore prope recto, umbonibus de- 

 pressis ; auriculis magnis caudatim productis, latere posterioria valde incurve. 



The peculiar separating character of the Hyrianse as distinct from the Unioninse, 

 is, that the um bones or bosses are sulcated, not longitudinally but, if at all, trans- 

 versely. The present decidedly new species reminds us of the common Mytilus 

 Hirundo of Linneus, both in shape and colouring. It is triangularly oblong, striated 

 by the lines of growth, and of a deep rich brown, with the interior pearly. It differs 

 from the H. Avicularis in its more lengthened shape, the comparative sraallness and 

 deeper incurvation of the side of its posterior wing, the greater straightness of the 

 hinge margin and consequent less projection of the wide umbones. Size three inches. 

 Locality ? 



Sub-Family— ANODONTIN^. 



Cardiual teeth none ; lateral teeth extending along the hinge, or entirely wanting : hinge 



margin generally winged. 

 Genus — Anodon. Doubly winged : no lamellar or other teeth. 



ANODON SINUOSIS. CURVED ANODON. 



Plate XVI. 



Testa ovali, oUvacea, iiieeqnilaterali, trausversim striata ; auterius, superne incurva, coar- 

 colata, prope truncata ; marginis inferioris medio, incurve ; linea eai-dinali undato- 

 sinuosa : natibus prominulis, Ise^-igatis, erosis : interiore facie margaritacea. 



Anodon Shmosa, Lam. Ans. sans V. 6. p. 97 ■ no. 14. Enc. Met. 203. fig. 2. a. b. 



