276 Mollusca of Middlebury, Vt. and Yicinity. 



species is quite common. A species of Limax also occurs of the 

 same size. 



Anodonta. 



A. Benedictensis, Lea. This species occurs only in Lake 

 Champlain, where it is abundant. 



A. cataracta, Say. At Wallingford, Yt., a very few specimens 

 have been obtained. 



Two other species of Anodonta occur, which I have not been 

 able to identify with any species known to me. One of them re- 

 sembles A. Wardiana^ Lea. 



Alasmodonta. 



A. ar'oiiata, Barnes. That this species is quite distinct from 

 the margaritifera of Europe, I have had an opportunity of seeing 

 from a specimen of the latter in the cabinet of Dr. Gould. 

 Barnes's species occurs in Onion river, at Burlington. 



A. rugosa, Barnes. This species occurs In Otter Creek and 

 Lake Champlain, but is not common. 



A. undulata, Say. This species occurs in Otter Creek. 



Unio. 



U. alatus, Say. Abundant in Lake Champlain. 



U. gracilis, Barnes. Common in Lake Champlain. 



U. compressus, Lea. This species occurs, well characterized, 

 in a rivulet a few miles west of this village. In the east part of 

 this town are specimens which diifer so much from the common 

 type as perhaps to constitute a new species. 



U. rectus, Latn. This species occurs rarely in Lake Cham- 

 plain. 



U. ventricosiis, Barnes. This species is rather common in 

 Lake Champlain. It is subject to great variations of form. 



U. luteolus. Lam. This species is very abundant in Lake 

 Champlain. Its variations in form, although less than in the pre- 

 ceding, are considerable. In both, however, the most marked 

 are those of sex. 



U. complanatus. Lea. Very abundant in Lake Champlain and 

 elsewhere, but I have not seen one with a white nacre. Rayed 

 speci^nens are sometimes seen. 



I have found in Lake Champlain a single specimen of another 

 species, which is unknown to me. 



