44 LAND AND FRESH-WATER SHELLS OF N. A. fPART IIL 



applied by Wood to a flgnre of i^ubcarinata. I also give a fac- 

 simile (fig. 8(5) of Lister's ligure. 



Paludina Iceierodropha of Kiiiland's Ohio Eeport is referred 

 by Gould (Boston Proc. 1, 32) to 3[el. ponderosa. Judging from 

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

 It is so considered by Ileeve. This figure is copied in my fig. 

 ^1, while the description furnished Tappan by Dr. Kirtland is as 

 follows : — 



Paludina heterostropha, Kiktlaxd, I.e. — Sinistral; aperture more than 

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

 Fig. 87. depressed, apex generally truncate ; whirls 5 ; aperture ovate, 



with its superior extremity curved towards the body whirl, 

 within bluish-white ; epidermis greenish horn color, usually 

 coated with ferruginous clay. Length | 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 examination 

 found it to be specifically distinct. It never attains more 

 than half the length of that species ; its spii'e is never de- 

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



To the copy of the description of Paludina decapitata, of Mr. 

 Anthony, given below, I am able to add Fig. 88, drawn from 

 the type, which he kindly loaned lue for the purpose. I do not 

 consider this a well-established species. The single specimen on 

 which it is founded is evidently an undeveloped specimen in a 

 very imperfect state. The spire is eroded, the shell presents the 

 appearance of belonging to a small ill-favored individual of M. 

 decisa. However, the only information we have regarding it, 

 given below, may serve to identify it, should it appear in future. 



Paludina decapitata, Anthony. — Shell globular, thin, of a light green 

 color ; spire truncate, but never elevated under any circumstances, com- 

 posed of about four very Hat whirls ; aperture broad. 

 Fig. ^8. ovate, one-half the length of the shell, within dusky white ; 



columella regularly but not deeply rounded, with a slight 

 deposit of callus, and having a very small linear umbilicus 

 at base. 



Tennessee. My Cabinet. 



A single specimen only is before me, and therefore I 



claim it as a new species with some hesitation ; it seems 



to me, however, too unlike any of the ordinary forms in 



this genus to warrant its being included with any of them ; it is the 



most globose of any species hitherto published, if we except the small, 



round forms wliich were long since removed, and very properly too, to 



