LYMNVEimE OF NORTH AMERICA. 229 



Types : Say's type cannot be found. A specimen received from 

 Say is No. 58824 in the collection of the Academy of Natural Sciences, 

 Philadelphia ; smithsoniana Lea, six specimens, Smithsonian Institution, 

 No. 118700 ; fcrrissi, one specimen, Chicago Academy of Sciences, No. 

 3458. 



Type Locality : Indiana for caperata; Loup Fork of the Platte 

 River for 'smithsoniana; Rock Run, Joliet, Illinois, for ferrissi. 



Animal : Black or bluish black, lighter below and minutely flecked 

 with small, whitish dots, which are scarcely visible except on the top 

 of the head; head distinct; tentacles short, flat, triangular; foot short 

 and wide, 8 mill, long and 3 mill. wide. The animal is very rapid 

 and decisive in its movements. 



Jaw (pi. VI, fig. L) : Wide and rather high, the median swelling 

 occupying about one-third of the width; ends rather bluntly rounded. 



Radula (plate IX, figure J) : Formula: 5 8_° 7+ j± T+ ! + } + f +J ± ¥+ £_o T 

 (32-1-32) ; central tooth with a rather broad, spade-shaped cusp ; lateral 

 teeth bicuspid, the mesocone very broad, the ectocone very small and 

 placed rather high ; intermediate teeth tricuspid, the entocone of the 

 ninth, tenth and eleventh teeth very small and acute, placed high on 

 the mesocone, which is smaller than in the lateral teeth; the twelfth 

 tooth is very much modified, with the three cusps about equal in size ; 

 marginal teeth claw-like, the entocone split to form from three to four 

 small cusps, the mesocone and ectocone reduced in size and a small 

 cusp appearing prominently above the ectocone. There are over eighty- 

 five rows of teeth. 



In the Mollusca of the Chicago Area, the writer figured a radula 

 with but seven laterals, but the normal number is eight. The radula 

 figured on page 272 for the short-spired caperata is incorrect, no speci- 

 mens being subsequently studied which gave such a formula. 



Genitalia (plate XIII, figure D) : Male organs: Penis short, 

 two-thirds the length of the penis-sac, which is large and cylindrical ; 

 vas deferens a trifle longer than penis and penis-sac combined; pros- 

 tate duct about the length of penis and penis-sac ; prostate large, ovately 

 cylindrical, rounded at both ends ; retractor muscle of penis enlarged 

 at its insertion in the columellar muscle; penis-sac retractor enlarged 

 at its junction with the penis-sac, about three-fourths the length of 

 the penis retractor; the two retractors are joined at their insertion in 

 the columellar muscle. 



Female organs : Lower portion of oviduct narrow, short ; first 

 accessory albuminiparous gland very large, bulbous ; receptaculum 



