LYMNIDZ 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 7S | $ re z 
28.50 12.00 13.50 7.50 “  Baker’s Iowaensis 
45.00 16.00 18.00 EO % Hald. Fig. 3 
47.00 15.00 18.00 9.50 ~ Calumet River, Chicago 
39.50 13.50 15.00 SO 0lee ies = ~ $ 
36.50 11.50 15.00 S00 ee 3 ¢ ef 
32.00 12.50 15.00 0 rs a s 
33.00 11.50 13.00 7.00 “ Lake Albert Lea, Minn. 
33.00 11.50 14.00 7.75 “ Winnebago Co., Ill. 
39.00 12.50 16.00 S1000eae e oe 
37.00 12.50 14.50 7200) se Romeo, III. 
31.00 11.50 14.00 002 =a cs * 
31.50 10.00 12.50 ESO) Lockport, Ill. 
27.50 10.50 12.50 6550) ee r. * 
19.50 8.00 9.00 4200) & Crystalleakes iil: 
21.00 8.00 10.00. 500) es . 
23.00 8.50 10.50 LOO) as a ns A 
26.50 10.50 12.50 5.50- -* i 6 © 
28.00 10.00 12.00 G00) 23 % 3 a 
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 Locarity: Reflexa, Lake Superior; iowaensis, Muscatine, 
Iowa; crystalensis Crystal Lake, McHenry County, III. 
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. 
RapuLaA: (Plate IX, figure A) Formula: 234 54,;4314)444+ 
Ti4 31547123 (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 
