﻿268 DESCRIPTIONS OF 



By the examination of Spix's description and figure it will be seen at once that our 

 species differs in many points from his obtusa, tab. 22, fig. 3 and 4. It is more com- 

 pressed, is without rays and has a striate and wrinkled surface. In the two specimens 

 before me the beaks are eroded and therefore no character can be given of them. 

 Both have a rather broad margin, and the triangular fosset at the end of the ligament 

 which is so characteristic of the South American and Central American species. This 

 specimen was kindly given to me by Dr. Ruschenberger. 



Unio Canadensis. PI. 44, fig. 148. 



Testa laevi, triangulari, subcompressa, insequilaterali, postice obtuse angulata ; valvulis subcrassis, antice 

 crassioribus ; natibus subprominentibus ; epidermide lutea, postice radiataj dentibus cardinalibus parvis, 

 erectis crenulatisque ; lateralibus longis, curvis larnellatisque ; margarita vel alba, vel rosea, et irides. 

 cente. 



Shell smooth, triangular, rather compressed, inequilateral, obtusely angular behind ; 

 valves rather thick, thicker before ; beaks rather prominent ; epidermis yellowish, 

 radiated behind ; cardinal teeth small, erect and crenulate ; lateral teeth long, curved 

 and lamellar ; nacre white or pinkish and iridescent. 



Unio Canadensis, Lea. Proc. Acad. Nat. Sci., 1857, p. 85. 



Hob. — St. Lawrence River, near Montreal. M. Carey Lea. 



My cabinet and cabinet of the Academy of Natural Sciences, Philadelphia. 

 Diam. 1*3, Length 2-1, Breadth 3*3 inches. 



Shell smooth, triangular, rather compressed, inflated towards the beaks, inequi- 

 lateral, obtusely angular behind, obliquely rounded before; substance of the shell 

 rather thick, thicker before ; beaks rather prominent ; ligament rather long and thick ; 

 epidermis yellowish, radiated behind, and with distant marks of growth ; umbonial 

 slope raised and somewhat angular ; posterior slope rather wide and raised into a 

 carina ; cardinal teeth small, erect and crenulate, single in the right and double in 

 the left valve ; lateral teeth long, curved and lamellar ; anterior cicatrices distinct 

 and deeply impressed ; posterior cicatrices confluent and slightly impressed ; dorsal 

 cicatrices situated on the plate within the cavity of the beaks and posterior to the 

 cardinal tooth ; cavity of the shell deep and wide ; cavity of the beaks deep and 

 angular ; nacre white or pinkish and iridescent. 



Remarks. — This species is closely allied to ovatus, Say, but it is smaller and more 

 compressed, and the posterior slope is not so much flattened. The specimen before 

 me has pinkish teeth. There are no rays on the sides of it, but the posterior slope is 

 nearly covered with green rays and other individuals may be found with rays on the 

 sides. The beaks are too much eroded to distinguish the character of the undulations. 

 There are two specimens in the Academy of Natural Sciences, both of which are 

 rather smaller than the one figured here. 



