THE NAUTILUS. VI 1 



Pt3'sa elliptica minor Crandall, n. var. . . . .55 



Physa forsheyii Lea ........ 69 



Physa globosa Hald. . . . . . . . .71 



Physa grosvenorii Lea ....... 69 



Physa gyrina var. albofilata Ancey . . . . .54 



Physa gyrina Say ....... 45.112 



Physa heterostropha Say 28,112 



Physa heterostropha alba Crandall, n. var. . . .29 



Physa hildrethiana Lea ....... 45 



Physa integer Hald. ........ 56 



Physa lordi Baird . . . . . . . .44 



Ph} ? sa magnilacustris Walker . . . . . .43 



Physa microstoma Hald. ....... 70 



Physa niagarensis Lea . . . . . .55 



Physa oleacea Tryon ........ 45 



Physa parkeri Currier ....... 44 



Physa philippi Kiister ....... 29 



Physa plicata DeKay . . . . . . .29 



Physa pompilia Conrad . . . . . . ,70 



Physa rhomboidea Crandall, n. sp. . . . . 37, 44 



Physa sayi Tappan ........ 43 



Physa solida Phil 71 



Physa tenuissima Lea . . . . . . .71 



Physa troostiana Lea ....... 55 



Physa vinosa Gould ........ 43 



Physa walkeri Crandall, n. sp. . . . . 37, 57 



Physa warreniana Lea ....... 44 



Physse, the American 25,42,54,69 



Pisidium afflne Sterki, n. sp. . . . . .66 



Pisidium sargenti Sterki, n. sp. . . . . . .67 



Pisidium strengii Sterki, n. sp 126 



Pisidium variabile Prime ....... 132 



Pisidium virginicum Gmel. ...... 132 



Planorbis bicarinatus striatus Baker, n. var. . . . 120 



Planorbis parvus Say ...... 104, 128 



Planorbis trivolvis Say . . . . . . .103 



Pleurobema missouriensis Marsh, n. sp. . . . .74 



Pleurodonte acuta Lain. ...... 138, 140 



Pleurodonte acuta var. acutissima 140 



