194 THE CHICAGO ACADEMY OF SCIENCES. 



JAW : About twice as wide as high, with squarish ends and a 

 heavy convex median swelling. The jaw resembles that of Galba 

 palustris (see pi. VI, fig I). 



RADULA : (Plate VIII, fig. E) Formula : L\+ J+f +|+f +4+^ 

 (21-1-21). Central tooth with a sharp, spade-shaped cusp, the opaque 

 portion of the reflection strongly trilobate; lateral teeth eight in num- 

 ber, bicuspid, the mesocone very broad and modified on the inner side 

 by a strong swelling which probably corresponds in position to an en- 

 tocone ; ectocone small, broad, placed rather high up on the reflection ; 

 the seventh and eighth teeth are narrower than those preceding; the 

 ninth tooth is intermediate and is strongly tricuspid, the entocone being 

 very sharp, wide, and placed rather high upon the inner side of the 

 tooth ; marginal teeth beginning abruptly with the tenth tooth and six to 

 eight cuspid, acquired by splitting of the ectocone being high up on 

 the outer margin of the tooth; the mesocone persists throughout the 

 marginal teeth as a rather large cusp, while the entocone splits up into 

 several small denticles. The first lateral on one side in one membrane 

 had a double cuspid ectocone. There are about 80 rows of teeth. 



The radula of haldemani differs widely from that of any other 

 known species of this family and is approached only by Lymncsa ha- 

 ivaiensis Pilsbry, as mentioned on a previous page. 



GENITALIA: (pi. XI, fig. F) Male organs; penis-sac cylindrical, 

 2.25 to 2.60 mill, long and about .90 mill, wide; penis short, thick, 1.50 

 to 2.00 mill, long (4/6 to 4/7 the length of penis-sac) ; vas deferens 

 G.OO to 6.50 mill, in length; prostate duct 2.80 to 2.90 mill, long, en- 

 tering the prostate by a slight enlargement; prostate flatly cylindrical, 

 1.60 by .60 mill., its ends broadly rounded, the posterior portion very 

 narrow; penis and penis-sac retractors equal in length (each 1.65 in- 

 alcoholic specimen and 3.00 in fresh specimen), attached distally to 

 the columellar muscle; protractors of penis-sac three to four in num- 

 ber, two posterior and one small or two large anterior ; each muscle is 

 very slender and enters the penis-sac by several terminations. 



Female organs; receptaculum seminis large, rounded, with a duct 

 three mill, long, which enters the oviduct by an enlargement; first ac- 

 cessory albuminiparous gland large, ovate ; second accessory albumini- 

 parous gland very small ; free portion of oviduct large, short ; the other 

 organs not differing from those of the other Lymnseidse. 



The penis-sac retractor muscles exhibit some variation in their 

 insertion in the penis-sac (pi. XV, fig. E). In two examples (pi. XI, 

 F; pi. XV, E, 2) the muscle is split to form four rather widely sepa- 



