224 THE CHICAGO ACADEMY OF SCIENCES. 
situated centrally; concave margin with a strong median pro- 
jection; anterior surface smooth (Fig. 57, J). 
Radula formula: §+3-+8+4+8+3+8 (21—1—21); central 
tooth as usual, the central cusp not being as long as in the 
other species mentioned; laterals eight in number, the outer 
side cusp being longer than usual; marginals similar to those 
of retusa, excepting that in the first five the inner cusp is not 
bifid and there are but two outer side cusps; all of the cusps 
are very long and bear sharp cutting points (Fig. 57). 
Genitaha: Not examined. 
Distribution: ‘Canada to Georgia, west to Minnesota, 
Montana, Utah, Texas and California.” (Pilsbry.) 
Geological distribution: Pleistocene; Loess, 
Uv 
Fig. 57. 
Radula of SUCCINEA AVARA Say. (Jaw after Binney, radula original.) 
c, central tooth; 1,8, lateral teeth; 9, first intermediate marginal; 14 sixth 
marginal; J, jaw. : 
Habitat: Found plentifully under wet boards and logs 
and at the roots of vegetation situated in moist or wet locali- 
‘ties. The vegetation beneath old wooden bridges is always a 
good locality for this species. 
Remarks: Avarais distinguished from the previous species 
by its long spire and nearly round aperture. The movements 
of this species are always slow and deliberate, and it lacks the 
energetic motions of its relatives, ovals and retusa. Thesutures 
are sometimes very deep and somewhat channeled. The species 
is not very common, except in a very few localities, but is found 
sparingly everywhere. 
