1 AMNICOLA. 



Aninicola parva, Lea — Shell obtusely conical, rather thin, yel- 

 lowish, smooth, umbilicate ; spire short ; suture impressed ; whorls four, 

 inflated ; aperture large, nearly round. 



Springfield, Ohio. Diam. .15, length .18 inch. 



The shell described by Mr. Anthony as Paludina Cincinnatiensis, re- 

 sembles this species, but is more elevated in the spire, and is a larger 

 shell. It is more nearly allied to Amnicola orbiculata, herein described, 

 but may be distinguished by its being a smaller shell, and being less round 

 in the aperture. The base of the lip is disposed to be slightly angular ; 

 the aperture is about one half the length of the shell. {Lea.) 



Amnicola parva, Lea, Tr. Am. Phil. Soc. IX, p. 16 ; Proc. II, 34. — Halde- 

 MAN, Mon. p. 24. 



Amnicola Oljtlisa, Lea — Shell subcylindrical, rather thin, dark- 

 green, smooth, slightly jierforate ; spire short ; at the beaks very obtuse ; 

 sutures impressed ; whirls four, convex ; aperture small, nearly round. 



Ohio. Diam. .07, length .10 inch. 



This is among the smallest of the genus, and may at once be distin- 

 guished by its obtuse apex, which has the appearance almost of being trun- 

 cate. The whirls do not decrease regularly from the lower one to the 

 apex, the greatest diameter being apparently across the second whirl. In 

 form, therefore, it has the aspect of a Pupa. It answers partly to the de- 

 scription of Paludina Alleglianiensis, Green, but seems to differ in the trun- 

 cate appearance of the apex, and in its size. Two specimens were found 

 in a box, with some other small species, kindly sent me by Dr. Kirtland. 

 It is rather less than Pal. Nickliniana, but diifers from it in being less 

 tapering to the apex. It closely resembles P. viridis, Lam., but is rather 

 larger, and more obtuse. There were no opercula to examine in these 

 specimens ; aperture rather more than one-third the length of the shell. 

 (Lea.) 



Paludina obtusa, Lea, Tr. Am. Phil. Soc. IX, p. 13 ; Proc. II, 34. 

 Amnicola obtusa, Haldeman, Mon. p. 24. ■ 



Amnicola orlJiculata, Lea — Shell orbicular, rather thin, yellow- 

 ish, smooth, umbilicate ; spire short ; sutures much impressed ; whirls 

 five, inflated ; aperture large, round. 



Springfield, Ohio. Schuylkill? near Philadelphia. Diam. .18 length 

 .18 inch. 



This species is very nearly allied to Am. parva, and may prove to be 

 only a variety of it. The specimens before me are all larger, and they 

 appear to be more globose. The aperture is about half the length of the 

 shell. I found a single specimen of this species among many small shells 

 which were thrown together in a box, as being collected from our vicinity. 

 It may be possible it is an Ohio specimen gotten by mistake into the box. 

 Found also in Cayuga Lake. {Lea.) 



