42 Observations on the Terrestrial 



Limnophysa humllis, Say. 

 Southern pai'ts of the State. Very abundant near Portland. 



Limnophysa caperata, Say. 



Limnophysa catascopium, Say. 

 Very abundant in the vicinity of the mouth of the Androscog- 

 gin River, in company with Physa ancillaria, 



Radix columella, Say. 



Very common in the southern portions of the State, rare in 

 the interior. 



Radix ampla, Mighels. 



Found a few dead specimens of this species in Mud Lake, at 

 the northern part of the State, the original place of discovery. 

 I was led at one time to believe this a variety of L. catascopium. 

 Say, through its resemblance to L. decollata, Mighels, which I 

 believe to be a variety of L. catascopium. 



Radix decollata, Mighels. 



Having had specimens of this species from Dr. Mighels' original 

 collection, and having compared them carefully with modified 

 L. catascopium from that region, I see no reason to differ from 

 the opinion expressed by Haldeman in his " Monograph of the 

 LimnseidjB," in which he considers it a variety of L. catascopium. 

 The shortened spire and solid character of the shell is peculiar to 

 many specimens of L. catascopium from that vicinity. This 

 peculiar decollate form has not been found elsewhere in the State. 



PHYSIN^. 



Physa heterostropha Say. 



A very common species in all our brooks ; cold springs appear 



to be a favorite resort for this species. There appears to be no 



constant character in the digitations of the mantle margin; in 



