THE NAUTILUS. 



Physa elliptica minor Crandall, n. var 



Physa forsheyii Lea . 



Ph}'sa globosa Hald. . 



Physa grosvenorii Lea 



Physa g3 r rina var. albofilata Ancey 



Ph} r sa gj'rina Say . - . 



Physa heterostropha Say . 



Physa heterostropha alba Crandall, n 



Physa hildrethiana Lea 



Physa integer Hald. . 



Physa lordi Baird 



Physa magnilacustris Walker 



Physa microstoma Hald. 



Physa niagarensis Lea 



Physa oleacea Tryon . 



Physa parked Currier 



Physa philippi Kuster 



Physa plicata DeKay 



Physa pompilia Conrad 



Physa rhomboidea Crandall, n. sp. 



Physa sayi Tappan 



Physa solida Phil. 



Physa tennissima Lea 



Physa troostiana Lea 



Physa vinosa Gould . 



Physa walkeri Crandall, n. sp. 



Physa warreniana Lea 



Physae, the American 



Pisidium affine Sterki, n. sp. 



Pisidium sargenti Sterki, n. sp. . 



Pisidium strengii Sterki, n. sp. . 



Pisidium variabile Prime 



Pisidium virginicum Gmel. 



Planorbis bicarinatus striatus Baker, n. var. 



Planorbis parvus Say 



Planorbis trivolvis Say 



Pleurobema missouriensis Marsh, n. sp. 



Pleurodonte acuta Lam. 



Pleurodonte acuta var. acutissima 



25 



55 

 69 

 71 

 69 

 54 

 45, 112 

 28, 112 

 . 29 

 . 45 

 . 56 

 . 44 

 . 43 

 . 70 

 . 55 

 . 45 

 . 44 

 . 29 

 . 29 

 . 70 

 37,44 

 . 43 

 . 71 

 . 71 

 . 55 

 . 43 

 37,57 

 . 44 

 42,54, 69 

 . 66 

 . 67 

 . 126 

 . 132 

 . 132 

 . 120 

 104, 128 

 . 103 

 . 74 

 138, 140 

 . 140 



