Pulmonifera of Maine. 43 



some it is divided into thick lobes, in others it assumes the ap- 

 pearance of long lashes. The body varies in color from a light 

 olive green or yellow, to a dusky olive. Buccal plate thin, color- 

 less, triangular, longitudinally striate, cutting edge minutely 

 notched. I enclosed a specimen of this species in a small vial 

 filled with water and corked tight, for the purpose of seeing how 

 long the animal could exist without access to the air ; for some 

 time it continued very active in its attempts to procure air, and 

 in whatever position I changed the vial, it assumed a perpendicu- 

 lar position in crawling ; after the lapse of several hours it became 

 sluggish, and at the expiration of seventeen hours all parts of the 

 animal protruded from the shell, though it showed slight contrac- 

 tion on being placed in alcohol. 



Physa ancillaria, Say. 



Generally diffused throughout the State, though not so common 

 as the preceding species. 



Mighels mentions its occurrence in the northern parts of the 

 State. This species is extremely variable in its appearance, and 

 I have noticed in the State nearly all its varieties figured by 

 Haldeman in his Monograph of the Limnieidag. 



Physa gypina, Say. 

 Dr. Mighels mentions the occurrence of this species in the 

 State. I have never seen it, neither can I see sufficient grounds 

 for separating the form described as such from P. heterostropha. 



Physa fragilis, Mighels. 



We have every reason to believe this shell to be a variety of 

 P. ancillaria. The circumstances attending its discovery lead to 

 this belief The shell was found in a mill stream charged with 

 wood dust from a neighboring saw mill. In the waters above 

 the mill, P. ancillaria occurred in abundance, with no trace of P. 

 fragilis. This mill was afterward destroyed, and nearly synchro- 

 nous with this event was the entire obliteration of P. fragilis and 

 the recurrence of the normal form P. ancillaria ; nothing ap- 



