250 NEW YORK STATE MUSEUM 



Genus alasmidonta Say. 1818 



The shell is ovate, solid and inflated, shining, with strong beak 

 sculpture. Cardinal teeth thick and strong; the laterals are short, 

 sometimes not present. 



Alasmidonta calceola (Lea) Simpson 1900 (Fig. 186). Unio 

 c a 1 c e o 1 u s Lea (1830. P kilos, soc. Trans. 3 '.26^). Alas- 

 midonta calceola Simpson (1900. U. S. 

 nat. Tints. Proc. 22:668) 



\ ' ; Shell small, solid and inflated ; surface smooth ; 



L r -'' anterior end rounded; posterior end triangular; 



„. ,„. ., ., ^ dorsal marg-in oval tc the umbo, whence it has a 



Fig. 186 Alasmidonta ^ cs > 



^^^<^^o^^ deep inward curve, back of and under the beak; 



ventral margin straight; muscle impressions deep and well defined; 

 pallial line clear; beaks prominent, inflated, more or less sculptured. 



Locality. Goat island. 



Alasmidonta truncata (Wright) Simpson 1900 (Fig. 187). 

 Margaritana marginata var. truncata Wright 

 (1898. Nmitihts, 1 1 :i24). Alasmidontatruncata Simp- 

 son (1900. U. S. nat. inns. Proc. 22:671) 



Shell elongated, quadrangular and heavy; surface marked by dis- 

 tinct growth lines, which are crossed by transverse wrinkles on the 

 posterior slope; posterior end angulated; anterior end rounded; dor- 



^ 



Fig. 187 Alasmidonta truncata 



sal margin curved outward at the umbo; ventral margin straight or 

 nearly so; muscular impressions deep, particularly the anterior ad- 

 ductor; pallial line distinct; beaks large, prominent and incurved. 



