MOLLTISCA. 167 



shell measures: greater diameter 6.5mm.. height 2.75mm., aperture 

 height 2mm.. aperture width 1.75mm. 



Segmentina crassilabris, var. — A variation of the species was found 

 on Sand Point, on leaves on the bottom of the larger lakes (10), and 

 in a perennial swamp (19). This form has not so strong a callus on 

 the lip as has the typical form, nor is the lower lip so strongly carinate ; 

 it is even higher in proportion to its diameter. A representative 

 example measures: greater diameter 6.7omm., width 3mm., aperture 

 height 2.5mm., aperture width 2.25mm. 



Ancylidae. 



76. Ancylus fuscus C. B. Adams. — Only one specimen of this 

 species was found. It was obtained from a board which was floating 

 on the water in the ox-bow pond off the Pigeon River (22). This 

 shell is quite narrow and high, measuring: length 6mm., width 

 4mm., altitude 1.75mm.; the left slope is quite convex, while the 

 right is .straight. 



77. Ancylus parallelus Haldeman. — ^This shell was found in small 

 numbers in a cove on the south shore of Sand Point (8), in con.sider- 

 able abundance in the ox-bow pond off the Pigeon River (22) and in 

 the dead waters several miles up the same river (24), and from 

 mucky-bottomed portions of Rush Lake (11). In all of these places 

 the specimens were found on the under-side of lily-pads. The speci- 

 mens from Sand Point are narrow, and the sides are quite parallel; 

 those from Caseville and Rush Lake are more typical, are broader 

 and wider anteriorly. All of the shells are small; one of the larger 

 examples from Sand Point measures: length 4.25mm., width 1.25mm., 

 altitude 1.25mm.; one from Rush Lake: length 4mm., width 2.25 

 mm., altitude 1.50mm. 



Physidae. 



78. Physa ancillaria Say. — A few specimens of this species were 

 found on rocks in an old wharf near Little Oak Point. A represen- 

 tative example measures: altitude 11.5mm.. width 7.25mm., aperture 

 length 9mm.. aperture width 4mm. 



Physa ancillaria, var. — Two 'specimens of this species that are not 

 typical were brought up on the nets of the fishermen from about 

 twenty feet of water, a mile off the north shore of Sand Point (1). 

 One is a deformed shell, but apparently is the same form as the other, 

 which is a fragile shell, Avith the last whorl enlarged at the top so that 

 it swells considerably out of the line of the conical first whorls. In 

 shape it somewhat resembles the variety magnalacustris, but the last 

 whorl enlarges more abruptly at its upper end. It measures: alti- 



