LYMNJEHXE OF NORTH AMERICA. 



335 



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: 3 r _j_ F i +f+-y-+i+ 

 ^_|_f_|_ 7 ! _j_ 1 pJ T (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 



