180 THE CHICAGO ACADEMY OF SCIENCES. 



body whorl ; inner lip reflected and widely spreading in old specimens ; 

 umbilical chink very small in young or half grown individuals, but 

 wide and deep in fully adult specimens. The epidermis is somewhat 

 marked by light and dark lines of color, alternating. Nucleus of about 

 1^4 hyaline whorls, not differing in outline from those of Lymnaa 

 stagnalis appressa. 



Length. Breadth. Aperture length. Breadth. 



23.00 17.00 18.00 11.00 mill. 



20.00 15.50 15.50 9.50 " 



31.00 24.00 24.50 16.50 " 



26.50 21.50 24.50 14.00 " 



18.00 12.25 13.00 8.00 " (Half grown) 



15.00 10.00 11.00 7.00 " 



TYPE : Location unknown. 



TYPE LOCALITY : Not known to the writer. 



ANIMAL : Body flecked with small white spots ; mantle marked 

 by many black, irregular spots which show through the shell; head 

 broad, auriculate; tentacles very long, narrow, tapering; foot broadly 

 rounded anteriorly and acutely rounded posteriorly; 18 by 11 mill, in 

 a specimen of good size. 



JAWS: Superior jaw low and very wide, strongly arched, about 

 one-quarter as high as wide with a distinct rounded median projec- 

 tion about one-third the length of the entire jaw; lateral jaws not 

 differing from those of Lymncea stagnalis (PL VI, fig. D). 



RADULA : Formula : |. + f + f^f + i-Li_|-i-Lf-|--f--|_A_|_|2 

 (PL VII, fig. C) (5.0-1-50). Central tooth narrow, with a long 

 acute mesocone (C) ; first lateral tooth very broad, tricuspid, the 

 mesocone very wide, the entocone and ectocone small ; second to ninth 

 lateral teeth broad, bicuspid, the mesocone very wide, the ectocone 

 small and rather narrow ; the tenth tooth becomes tricuspid by the 

 splitting of the mesocone to form a small spade-shaped entocone; the 

 eleventh to thirteenth teeth are similar in form, the entocone, however, 

 approaching more nearly to the distal end of the reflection in the 

 twelfth and thirteenth teeth ; the fourteenth to eighteenth teeth have 

 a very long and narrow reflection, with two spade-shaped cusps at 

 their extremity and two small outer cusps about midway of the reflec- 

 tion; the nineteenth to twenty-first teeth are similar, excepting that 

 the cusps at the distal end vary from two to four in number ; the mar- 

 ginals from the twenty-third to the edge of the membrane are long and 

 narrow, with small cusps at their distal ends, and two small cusps on 

 the outer margin. There are from eighty to ninety rows of teeth. 



