192 PROCEEDINGS OF THE ACADEMY OF 
it entirely. The last two authors figure a retractor to the duct of 
the genital bladder, and so does Leidy (though in the description 
of the plates he refers it to the vagina). Lehmann figures a re- 
tractor also to the genital bladder itself. LLehmann’s figure of the 
genitalia of A. fuscus (pl. VI., fig. 2) agrees more closely with 
Leidy’s figure in all respects, indeed, but the position of the 
retractor penis, which Lehmann places at the top of the penis sac. 
His figure of the dentition of fwscus is nearer mine of the Boston 
specimens than is his of horéensis, though the transverse count of 
teeth is larger. Goldfuss’ figure of the dentition of A. hortensis 
also (1. ¢. pl. V., fig. 6) differs from my figure in the same way, 7. e., 
by the presence of an inner side cusp and cutting point to the 
lateral teeth. Thus I find it impossible to decide from the geni- 
talia whether to refer our species to fuscus or hortensis, though I 
incline to the former. From the dentition I should assuredly adopt 
the former name also. 
The jaw of the Boston specimen (pl. XVI., fig. 2) is thick, 
arcuate, ends but little attenuated; no median projection to the 
cutting edge: anterior surface with 8 stout, separated, unequal ribs, 
denticulating either margin. 
Lingual membrane (pl. V., fig.5) long and narrow. Teeth about 
31—1—81, with about ten perfect laterals. Centrals with the base 
of attachment longer than wide: reflection half as long as the 
base of attachment, bearing one long, stout cusp extending to the 
lower margin of the base of attachment, beyond which projects 
the stout cutting point: side cusps distinct, but small, with dis- 
tinct, small, stout cutting points. Laterals like the centrals, but 
unsymmetrical by the suppression of the inner, lower, lateral ex- 
pansion of the base of attachment, and the inner side cusp and 
cutting point. The marginals are low, wide, with one long, bluntly 
pointed, oblique cutting point, bearing a subobsolete smaller point 
low down upon its outer side. This subobsolete side cutting point 
is on some of the marginals much more developed. 
My figure a shows one central with its adjacent lateral, and 6 
and c marginals, the latter form near the outer margin of the 
membrane. 
From the above remarks it will be seen that in this genus, as in 
Limax, Zonites, and others, the lateral teeth are either bicuspid 
or tricuspid. The number of cusps does not seem a generic 
character. 
