244 THE CHICAGO ACADEMY OF SCIENCES. 
aperture roundly and regularly elliptical, continuous in many specimens, 
a trifle effusive at the lower end; outer lip thin, sometimes developing 
i) white deposit or varix a short distance from the edge; inner lip 
markedly and broadly reflected over the umbilicus, forming a broad, 
even expansion; parietal callus well marked, thick; umbilical chink 
well marked, open, axis straight, not twisted, thickened by shelly de- 
posit. 
Length. Breadth. Aperture length. Breadth. 
4.50 2.50 1.50 .50 mill. Type parva 
iD 4.10 3.50 150s) ype cunta 
6.00 3.00 2.50 125 Allegheny Co Pennt 
5.00 PAT 2.20 150 “~ Dyer, Indiana 
9.00 4.50 3.80 200m en Des Moines, lowa 
8.00 4.00 3.80 i909 ee 3 as 
7.50 4.00 3.50 Tea a a; 
7.25 3.00 3.00 150) P< of i 
6.25 3.10 2.90 IO ‘ 
119418, all immature; curta, four specimens, No. 118632; tazewelliana, 
location unknown. 
Type Locarity: Parva and curta, Cincinnati, Ohio; tazewelliana, 
Tazewell shore, Illinois River, [linots. 
Anima: Color blackish, very thickly dotted with fine white dots. 
The upper whorls are pinkish in the living animal, and the spotted 
mantle shows through the almost transparent shell. A specimen with 
head and foot protruded, measured as follows: 
Length of foot and head. Width of foot. Length of shell. 
4.25 2.00 7.00 mill 
JAw: Superior jaw a trifle more than three times as wide as high, 
not notably arched, with a small median swelling on the ventral margin ; 
the jaw resembles that of wmbilicata. 
RapuLA: Formula: $842444414442141%(24-1-24) ; central tooth 
with a rather long cusp; lateral teeth tricuspid, very wide, the small 
entocone forming by a splitting of the large mesocone ; ectocone rather 
large; the marginal teeth commence at the seventh tooth, in which 
the entocone and mesocone are about equal in size and appear at the 
distal end of the reflection; the typical marginal teeth begin with the 
tenth tooth, the distal end of the reflection becoming serrated, while 
the outer edge develops several small serrations. The marginal teeth 
are long and narrow, and there is considerable variation in the number 
and position of the individual cusps. Eighty-two to ninety-five rows 
o: teeth were counted. The general form of the teeth are not different 
from those of wmbilicata (pl. VII, fig. A). 

