THE NAUTILUS. Oi 



Physa anatina Lea. 



This is the most striking and beautiful species of the genus. It 

 was discovered in a northern tributary of the Arkansas river in Kan- 

 sas, in 1864, and in that locality it has its greatest development. 

 The extent of its distribution is unknown. It is plentiful around 

 Wichita, Kansas, and has been reported from Missouri, Arkansas, 

 Nebraska and Michigan. It probably inhabits all the intervening 

 territory. 



Distinguished by its sub-fusiform and symmetrical shape, smooth 

 and shining surface, pale color, six oblique whorls, impressed sutures, 

 and the malleations on the lower part of the last whorl of all adult 

 forms. Bi-annuan. 



Diameter ^ the length. 

 Physa brevispira Lea. 



Ottawa river, Canada West, furnished the type for this species in 

 1864. It is not numerous in any locality, and is seldom reported by 

 collectors. I have examples agreeing with Lea's figure from Lake 

 Nippising, Ont.. and shells from five other localities which I believe 

 belong here, although they differ in color and height of spire. Speci- 

 mens from Detroit river, Reed's Lake and Pent Water, Mich., are 

 good representatives of the species in size, color and all other char- 

 acters except that the spire is somewhat exserted. The Isle of 

 Mackinac furnishes a much larger white shell which I refer to the 

 same species. 



Distinguished by its globose form, opaque whitish color and dilated 



aperture. It has been sent to me as P. ancillaria and vinosa. An- 

 nuan. 



Diameter | the length. Aperture T 7 ^ the length of shell. 

 Physa walkeri n. s. PI. 2, fig. 5. 



Shell elongate-ovate, ashy horn color, texture rather coarse, whorls 

 four, very convex, sutures much impressed, spire much elevated and 

 tapering to an acute apex, aperture ovate, not expanded, -^ the length 

 of the shell, lip tortuous and evenly curved, inner margin thickened 

 with thin white deposit. Length 10 mm, width 6 mm. 



This little shell was sent to me by Bryant Walker, Esq., of De- 

 troit, Mich., having been collected by him at Petoskey, Mich., after 

 whom I take pleasure in naming it. It has also been sent to me 

 from three other localities in Michigan, and Rideau river, Ont. It 

 is allied to P. integer Hald, and fills the place between that species 

 and P. anatina Lea. 



