LYMN^EID^E OF NORTH AMERICA. 335 



Length. 



Breadth. 



Aperture length. 



Breadth. 





34.00 



11.00 



14.50 



5.50 mill. 



Say's type reflexa 



31.00 



9.50 



13.00 



4.50 " 



" " " 



28.50 



12.00 



13.50 



7.50 " 



Baker's Iowaensis 



45.00 



16.00 



18.00 



7.50 " 



Hald. Fig. 3 



47.00 



15.00 



18.00 



9.50 " 



Calumet River, Chicago 



39.50 



13.50 



15.00 



8.00 " 



" " " 



36.50 



11.50 



15.00 



8.00 " 



" " " 



32.00 



12.50 



15.00 



7.50 " 



" " " 



33.00 



11.50 



13.00 



7.00 " 



Lake Albert Lea, Minn 



33.00 



11.50 



14.00 



7.75 " 



Winnebago Co., 111. 



39.00 



12.50 



16.00 



8.00 " 



" " " 



37.00 



12.50 



14.50 



7.00 " 



Romeo, 111. 



31.00 



11.50 



14.00 



7.00 " 



" " 



31.50 



10.00 



12.50 



5.50 " 



Lockport, 111. 



27.50 



10.50 



12.50 



6.50 " 



" " 



19.50 



8.00 



9.00 



4.00 " 



Crystal Lake, 111. 



21.00 



8.00 



10.00 



5.00 " 



" " " 



23.00 



8.50 



10.50 



5.00 " 



" " " 



26.50 



10.50 



12.50 



5.50 " 



" " " 



28.00 



10.00 



12.00 



6.00 " 



" " " 



Types : Reflexa, Academy of Natural Sciences, Philadelphia, two 

 specimens, No. 58639 ; iowaensis, coll. Bryant Walker, five specimens, 

 No. 2223 ; cotype, Chicago Academy of Sciences, one specimen, No. 

 23520; crystalensis, Chi. Acad. Sci., eight specimens, No. 23634. 



Type Locality : Reflexa, Lake Superior ; iowaensis, Muscatine, 

 Iowa ; crystalensis Crystal Lake, McHenry County, 111. 



Animal : Similar to palustris; the foot of a medium-sized speci- 

 men measured 12.50 mill, long and 6.50 mill. wide. 



Jaw : Similar to that of palustris. 



Radula: (Plate IX, figure A) Formula: ^4_ ¥ A ¥+ §-Hy--Hr+ 

 -V-+f+3-4-r-4- 3 6 (40-1-40) ; lateral teeth bicuspid, the mesocone long 

 and rather wide, the ectocone small and wide; the first lateral tooth 

 is wider than those which follow ; intermediate teeth four in number, 

 tricuspid, the entocone small, placed toward the lower margin of the 

 mesocone ; a small cusp appears on the outer margin of the ectocone ; 

 marginal teeth long, narrow, oblique, 4 to 6 cuspid at the distal end, 

 causing this part of the tooth to resemble a comb. The cusps are very 

 irregular in size. There are over 100 rows of teeth. In one mem- 

 brane examined, the first lateral to the right of the center tooth had 

 a bifid ectocone. In another specimen there were 15 laterals on the 

 right side of the central tooth and 14 laterals on the left side; in all 

 membranes examined the last two (generally 12 and 13) laterals have 



