84 



tion, evidentl}^ mature and all alike, two millimeters long, of 

 pale horn color, transparent. It is not a juvenile form of 

 some Ancylus, as has been suggested, its shape being dif- 

 ferent from all Ancj'li living here, which have been collected 

 and examined by the hundreds, in all stages of growth, in 

 the last 5'ears. This species also has probably a wider distri- 

 bution, but is quite difficult to find. It has not 3-et been 

 named. 



About five years ago, among numerous Pupidae kindly 

 .sent by Mr. A. Pettingell, of Hudson, O., two specimens of 

 a small Vertigo were found, different from all species known. 

 They were mature and exacth' alike; j'et it was considered 

 un.safe to establish a new species upon them. This year a 

 few more were seen among materials collected in the moun- 

 tains of North Carolina b}- Prof. A. Wetherby, formerly of 

 Cincinnati, and sent for examination, and thus the validity 

 of the species was confirmed. Probably it has its main dis- 

 tribution in the North, and extends southward in the Alle- 

 ghenies, as so many other animals and plants do. It is 

 named Vertigo viinuscula. 



Ad 2. Geographical distribution. It would reach far 

 beyond the time, and space allowed if we would enter into a 

 discus.sion on the geographical distribution of the Unionido', 

 the most conspicuous and most interesting group of our 

 Mollusca, and possibly some one better qualified will prepare 

 a paper for one of the future sessions of the academy on this 

 subject. In the meantime as much material should be 

 brought up as possible from all our waters: rivers, , creeks, 

 canals, lakes, ponds and pools, with notes on the nature of 

 the habitats. Only a few species may be mentioned here: 

 IJyiio le7is Lea, and U. circidiis Lea, are frequently mistaken 

 for each other, as in fact they have much resemblance. Partic- 

 ular attention should be paid to the female of the latter and 

 their branchial uteri. In Muzz3-'s pond, Portage County, 

 probabl}- in the Cu5'ahoga drainage, with sandy and peat}' 

 bottom, a form of Unio nasutiis Say, has been collected, in 

 October past, which Mr. Chas. T. Simpson, of the U. S. 



