MUSEUM OF COMPARATIVE ZOOLOGY. 37 
Triodopsis Sanburni. 
Plate I. Fig. 9; Plate III. Fig. 3. 
Shell narrowly umbilicated, globose, depressed, thin, sparsely hirsute, with 
distant, scarcely perceptible wrinkles of growth, yellowish horn-colored ; whorls 
five and one half, slightly convex, the last hardly descending, beneath convex ; 
aperture oblique, lunate, trilobed, with a heavy, prominent, blunt parietal tooth ; 
peristome white, broad, reflected, almost covering the umbilicus, thickened, 
bearing on its right margin a large squarely truncated denticle, on its basal 
margin a stout, bluntly pointed denticle, the two denticles separated by a small, 
rounded sinus. Greater diameter, 11 mm.; lesser, 10 mm.; height, 5 mm. 
Kingston, Northern Idaho (J. Rand Sanburn). 
Lingual membrane as usual in the genus. Teeth 26—1-26, with about eight 
laterals on either side, the ninth tooth having its cutting point split, the eleventh 
in another membrane: centrals with slightly developed side cusps and decided 
cutting points: laterals like the centrals, but bicuspid: marginals long, low, 
with two very wide, blunt cusps, the inner much the larger, both bearing long, 
oblique, irregularly bifid or trifid cutting points. (Pl. III. Fig. 3.) 
Genital system with no accessory organs. Penis sac long, cylindrical, some- 
what attenuated at its apex, where it receives the vas deferens and retractor 
muscle: genital bladder long, narrow, suboval: duct to genital bladder stout 
below, gradually tapering above. The same arrangement is found in the geni- 
talia of the typical devius. 
This shell, found in quantities living by Mr. Sanburn, shows no variation 
excepting slightly in size. There are no individuals showing a transition to 
forms of Mullant. It is nearly allied to that species as described by Mr. Bland. 
It is, however, much less globose, and has its aperture very much more con- 
tracted by teeth. The parietal tooth is not long and curving, but erect and of 
equal width to its bluntly truncated top. The upper tooth on the peristome, 
opposite, not above, the parietal tooth, is also erect and bluntly truncated. The 
lower peristome tooth is bluntly triangular. The sinus between the two pa- 
rietal teeth is small and rounded. 
I have described the shell as hirsute, though no hairs were found on the scars 
which surely bore them. 
The general appearance of the shell is that of T. Hopetonensis. 
Triodopsis Harfordiana. 
Plate I. Figs. 6, 7%. 
Shell umbilicated, depressed, thin, shining, sparsely hirsute, greenish horn- 
colored, wrinkles of growth not prominent; whorls four and a half, hardly 
convex, the last scarcely descending, deeply grooved behind the peristome, 
hardly convex beneath ; aperture very oblique, lunate, trilobed, with a small 
