THE NATURAL HISTORY SURVEY. 185 
ribs; inferior margin with a large, well-developed median pro- 
jection (Fig. 39, J). 
_ Radula formula: 18+32+8+4+44+2+4+13 (28-—1—28); 
central tooth with a base of attachment almost as wide as high, 
much produced at the outer, lower corners; reflection tricuspid, 
the central cusp very long, reaching below the edge of the base 
of attachment, wide, the side cusps short and wide; lateral 
teeth similar to central tooth, but the inner lower angle of the 
base of attachment suppressed and the reflection bicuspid, the 
inner cusp long, reaching below the base of attachment, and 
the outer cusp short, but longer than in the central tooth; the 
transition teeth similar to the laterals but the cusps shortening 
and becoming more equal; marginal teeth narrow, long, bicus+ 
pid, the cusps of equal size. All of the teeth have well-devel- 
oped cutting points (Fig. 39). There are about 80 rows of 
teeth. <- 
Genitalia: Unknown. 
Distribution: Europe, Asia, United States south to Texas ; 
Southern Canada and Alaska. Palzarctic. 
Geological distribution: Pleistocene; Loess. 
Habitat: Found associated with Zonitoides arboreus, Punc- 
tum pygmeum, Bifidaria curvidens, etc., under stones and sticks, 
in old and rotting logs. It requires a moist locality. 
Remarks: Thisis oneof our most common mollusks. The 
specimens from this region are very constant, exhibiting little 
or no variation, and may be easily known by their rounded 
spires and closely coiled whorls. The animal is rather shy and 
crawls about with a wabbly motion as though the shell were 
too heavy forit. The writer has found it particularly abundant 
in the woods about Bowmanville, under and crawling over 
chips and fallen pieces of bark. Prof. Pilsbry has shown* that 
there are two species of Conulus which are generally mixed 
together, viz., the present species and C. chersinus Say, which 
is a shell with a much more turreted spire ‘and more closely 
coiled whorls. The teeth of the two species are widely differ- 
ent, the present species having the formula 28-I-28 (original), 
30-1-30 Binney, while chersimus has 18-1-18 according to Morse. 
I feel certain that Morse had chersinus when he examined the 
dentition, for the reason that a number of personal examina- 
tions of undoubted fulvus a// gave 28-1-28. The present 
species is found throughout the area. 
*The Nautilus, Vol. XII, p. 113. 
