384 THE CHICAGO ACADEMY OF SCIENCES. 
environs of Philadelphia; intertexta, outlet of Black Lake, Holland, 
Michigan. 
ANIMAL: Yellowish or blackish, covered with small whitish 
flecks ; foot about as long as the aperture, wide, rounded behind; ten- 
tacles lighter colored at their tips. 
Jaws: (Pl. VI, figs. K., M.) Superior jaw arched, very wide, 
low ; ends acutely rounded; central lobe narrow, acute. 

Raputa: (Pl. IX, fig. 1). Formula: 2%4+ 5474344434 -3474 #4 
(35-1-35) ; central tooth with a rather long acute cusp; lateral teeth 
rather narrow, bicuspid, the mesocone very large, spade shaped, the 
ectocone small and rather wide; the tenth to twelfth (transition) 
teeth are wide and tricuspid, the entocone splitting off from the meso- 
cone, and gradually becoming larger; the thirteenth tooth (transition) 
is very wide, the entocone and mesocone are subequal and very acute; 
the true marginals begin at the fourteenth tooth which develops two 
to three small cusps on the entocone; outer marginals irregularly 4 
to 5 cuspid, the cusps being confined to the distal end of the tooth 
on the extreme outer teeth; the marginal teeth have one or two small 
cusps high up on the outer margin. The teeth are crowded on the 
membrane, fitting more closely than in Galba palustris. There are 
about 105 rows of teeth. 
Catascopium exhibits some variation in the position of the lateral 
teeth. Normally the lateral teeth seem to be nine in number, but in 
one specimen there were ten laterals, in another eleven laterals; one 
specimen from the Genesee River, Rochester, N. Y., had a radula 
with fifteen laterals on the left side and twelve laterals on the right 
side. Binney (op. cit. p. 55) figures 17 laterals, but this is evidently 
an error, as no Stagnalis has been seen with so large a number of 
lateral teeth. 
GENITALIA: (PI. XII, fies B). 
Male organs: Penis slender, usually as long as the penis-sac, 
which has a much larger diameter than the penis; vas deferens about 
twice the length of the penis and penis-sac; penis retractor long (1.50 
to 3.25 mill.) and slender; penis-sac retractor generally a trifle shorter 
(1.50 to 2.10 mill.) and thicker than the penis retractor; both re- 
tractors are inserted at the same point in the columellar muscle; pro- 
‘tractor muscles variable in number; the prostate is very large, flatly 
cylindrical, narrowing at the posterior end; the duct of the prostate 
is about half the length of the vas deferens, and enlarges slightly as 
it enters the prostate. 
