Quarterly Journal of ConcJiology. 387 



shell. It is much shorter and more conical than reflexa 

 proper. Another var. of reflexa is found near West Liberty, 

 in this county, with a peculiarly inflated or contorted 

 aperture. 



This var. approaches reflexa in size and general appear- 

 ance except the aperture. 



L. DESIDIOSA, Say. Were very abundant in a small pond near 

 this city. The pond is on Mad Creek bottom and in times 

 of very high water the creek runs through the pond. Two 

 years ago an unusual freshet occurred and seemed to wash 

 away every shell from the pond and I have found them no 

 where else. The specimens I found there are very fine ; 

 dark epidermis, which however may not be the real color; 

 10 mm. long. 



L. CAPERATA, Say. Common ; foot of animal yellowish, too large 

 to be entirely withdrawn in the shell ; light horn color, 

 body-whorl tumid, a sort of open umbilicus, aperture 

 lateral, about 15 mm. long ; muddy margins of ponds. 



Physa gyrina. Say. Rai-e. Our Physas are so variable in form 

 I am hardly certain about any of tliem ; grassy ponds. 



P. HETEROSTROPHA, Say. Abuudnnt along the margins of our 

 ponds. I found a remarkably tumid var. very fragile, 

 crawling about, under and over the ice in the spring. 



Planorbis trivolvis, Say. Abundant in all our ponds. 



P. EXACUTUS, Say. Abundant in some ponds. Last spring, soon 

 after the ice melted, I found thousands of them floating on 

 the water in what is known here as the Pond-Lily Pond. 

 They soon disappeared and have been difficult to find 

 since. They all look black. 



P. DEFLECTUS, Say. Abundant in Muscatine Slough and Kfokuk 

 Lake. They are covered with hairs apparently in regular 

 rows. TJie shell is certainly closely like P. aibus. 



