26 VIVIPARA. 



tion proves to be sufficiently distinct to form a new species. On account 

 of its color I call it 



Paludina cornea. — Shell ovate-conic, thin, opaque, greenish horn color; 

 whirls 5, subrounded ; sutures deeply impressed. 



This species has an obtuse apes ; the last whirl is one- third longer than 

 the others ; each of them has a kind of flattening (aplatissiment) which 

 forms a balustrade (rampe) around the spire, whose sutures are deeply 

 impressed. The striae of growth are vertical and fine. The aperture is 

 oval. Horn colored, with a greenish tinge ; the interior of the mouth and 

 lip is white. 



The largest individual was 11 lines in length. (^Valenciennes.) 



Paludina heterostropha of Kirtland's Ohio Report is referred 

 by Gould (Boston Proe. I, 32) to Viv. j^onderosa. Judging from 

 the figure given of it by Tappan, I would rather refer it to decisa. 

 This figure is copied in my fig. 39, while the description furnished 

 Tappan by Dr. Kirtland is as follows : — 



Paludina heterostropha, Kiktland, 1. c. — Sinistral; aperture more than 

 half the length of the shell. Shell subglobose, ovate ; spire 



Fig. 39. depressed, apes generally truncate ; whirls 5 ; aperture ovate, 

 with its superior estremity curved towards the body whirl, 

 within bluish-white ; epidermis greenish horn color, usually 

 coated with ferruginous clay. Length f inch. 



This shell frequently occurs in Mill and Yellow Creeks, 

 tributaries of the Mahoning River. I formerly considered it 

 a mere variety of P. decisa, Say ; but on further esamination 

 found it to be specifically distinct. It never attains more 

 than half the length of that species ; its spire is never de- 

 pressed, and it is always heterostrophal. (Tappan.) 



Paludina microstoma, Kirtland, is added to the synonymy on 

 authority of Mr. Anthony, who tells me Prof. Kirtland described 

 it before meeting with the description of integra. On seeing Mr. 

 Anthony's cabinet he was at once convinced of their identity. 



Fig. 40. Paludina microstoma, 1. c. — An undescribed species 



of Paludina, found frequently associated with the P. 

 decisa, and distinguished by its elongated spire and 

 small mouth. (Kirtland.) 



Paludina rufa, Haldeman, is said by him (1. 

 c.)-to be distinguished by a reddish color and 

 entire apex, but may be a variety of Pal. decisa. 

 The reddish or pinkish tint within the aperture 

 (sometimes divided into bands) appears to dis- 

 Paiudina rufa. tiuguish this form of the species, which occurs 



