GASTROPODA. 907 
Conradella fimbriata.] 
of it more gentle, and the edge of the umbilicus more narrowly rounded. The 
ventral side of the volutions being flatter, the umbilicus therefore is not only more 
abrupt at its circumference, but also a little smaller. The transverse imbrications, 
though not quite so oblique, are similarly disposed, but the serrations are broader 
and fewer in number, there being on each side only six or seven, to ten or eleven 
in C. obliqua. In C. compressa Conrad the transverse imbrications are but little, if 
at all, oblique, and the dorso-ventral diameter of the whorls the greater, while for 
C. similis the opposite is true. 
Formation and locality—Upper part of the Black River group, in Mercer and Boyle counties, Kentucky. 
Collection.—H. O. Ulrich. 
CoNRADELLA FIMBRIATA, 2. Sp. 
PLATE LXII, FIG. 66; PLATE LXVII, FIGS. 7—10. 
Shell discoid, from 18 mm. to 25 mm. in diameter. Volutions about three, 
enlarging more rapidly than usual for the genus, very strongly and rather abruptly 
carinate, broadly subcordate in section, wider than high, narrowly rounded in the 
lower part of the sides; umbilicus comparatively small, equalling two-fifths of the 
diameter of the shell; slit extending nearly a half-volution posterior to the apertural 
margin. Aperture abruptly expanded at frequent intervals, the expansion left 
behind forming transverse, imbricating, folded lamellx, the anterior edges of which 
are strongly serrated and project, collar-like, 3 or 4 mm. forward and outward from 
the surface of the last volution. Hach expansion has seven folds, the lower one 
faint, the upper ones strong. Occasionally a smaller one is developed between each 
pair of the latter. The entire surface covered by very fine longitudinal and trans- 
verse lines. All the transverse markings cross the volutions obliquely. When, as 
is generally the case, the projecting lamelle are broken away, the surface presents 
two or three more or less obscure revolving ribs on each side of the prominent keel. 
Greatest width of last volution, without the apertural expansion, in a specimen 25 
mm. in diameter, about 12 mm.; with the expansion about 18 mm.; hight of 
aperture about 15 mm. Intervals between imbrications varying on the outer 
whorls between 1 and 2 mm. 
When the apertural expansions are broken away this shell reminds one greatly 
of C. similis, the only difference being that the whorls enlarge more rapidly. But 
the perfect shell cannot be confused with any other, the great extent of the over- 
lapping expansions giving it a very striking appearance. 
Formation and locality.—Stones River group (Vanuxemia bed), Minneapolis, Minnesota, and Dixon, 
Illinois. 
Collections.—Geological and Natural History Survey of Minnesota (about 22 specimens); E. O. Ulrich 
(6 specimens). 
Museum Register, Nos. 653, 5110, 8724. 
