184 PROCEEDINGS OF THE ACADEMY OF [1876. 
tapering to its apex, where it receives the vas deferens and the 
retractor muscle. There is a long, stout, dart sac, containing a 
delicate, arrow-like dart of the same form as figured by Leidy for 
Zonites ligerus (Terr. Moll., U.S. I.). 
The absence of the caudal mucuspore removes the species from 
Zoniies, nor can it be placed in any recognized genus. 
Limax Hewstoni, J. G. Coop. 
California. Dr. Cooper. 
PLV1I., fig. F, represents the genitalia of this species, which I have 
recently drawn from specimens kindly furnished by Dr. Cooper. 
For description, see Ann. Lyc. Nat. Hist. of N. Y., XI., p. 22. 
Limax campestris, Binney, var. occidentalis. 
California. Dr. J. G. Cooper. (See Proc. Acad. Nat. Sci. of 
Phila., 1872, 146, pl. IIL., fig. oc.) 
In outward appearance, in genitalia and in jaw, this form can- 
not be distinguished from the eastern form. Its hingual membrane 
has 35—1—35 teeth, 13 being laterals. On some of both the inner ~ 
and outer marginals I can detect the side spur which in the eastern 
form I have only observed in the outer marginals. In this par- 
ticular, occidentalis is more nearly allied to LZ. montanus, Inger- 
soll,! but when the value of differences in such slight details 
becomes known, I believe all three species will be found identical. 
Pl. VL., fig. x, 6, gives two inner marginals. 
Onchidella borealis, Dall. 
Alaska. Dr. W. H. Dall. . 
In three specimens examined I found a jaw (pl. VI., fig. BB), low, 
wide, slightly arcuate, ends scarcely attenuated, blunt, anterior 
surface ribless. 
Lingual membrane (pl. VL., fig. EE) long and wide. Teeth about 
61—1—61, arranged strongly en chevron. The central tooth is 
large, longer than wide, truncated above, expanded below its 
middle, and incurved at the basal margin. The reflection is large, 
tricuspid, each cusp bearing a decided cutting point. The side 
teeth have a long, narrow base of attachment, a small portion of 
its upper portion thrown outwards, the balance curving inwards, | 
giving an irregular bow-shape to the whole base of attachment— 
i This is the species indicated by meas LZ. Ingersolli, in Proc. Acad. Nat. 
Sci. Phila., 1875, 176. | 
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