25O 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). U n i o 

 c a 1 c e o 1 u s Lea (1830. Philos. soc. Trans. 3 .26$). A 1 a s - 

 ggg _ midonta calceola Simpson (1900. U. S. 



'*v|f nat. mus. Proc. 22:668) 



f . Shell small, solid and inflated; surface smooth; 



L m_- "' anterior end rounded; posterior end triangular; 



tt-„ 10( - .1 ■/■ * dorsal margin oval to the umbo, whence it has a 



Fig. 186 Alasmidonta & ' 



calceola 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 trimcata (Wright) Simpson 1900 (Fig'. 187). 

 Margarita n a marginata var. truncata Wright 

 (1898. A T aiitilus, 1 1 :I24). Alasmidonta truncata Simp- 

 son (1900. U. S. nat. mus. 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- 



• 



S- 



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, 



