Geology and Paleontology. 1017 
one large, strongly inflated ; lower portion rounded ; upper surface 
somewhat flattened, and marked by a distinct revolving groove or 
depression, which becomes obsolete on the second volution, or 
almost before reaching it. Suture from nearly linear at the apex, 
to comparatively deeply channeled below; aperture orbicular; 
outer lip thick, entire ; columella lip very thick, especially the lower 
portion. Surface of body volution ornamented by strong sub-equi- 
distant, oblique, sinuous lines. 
Dimensions: vertical height, 2 mm. ; greatest width, 2 mm. 
Position and locality: base of Rockford Shales, Hackberry, 
n 
has also a slightly more curved outline than the two upper ones; 
suture well defined; aperture imperfect, but apparently discoid. 
Surface marked by simple straight lines. : 
imensions: vertical height, 2? mm. ; diameter at base, 1? mm. 
; Position and locality: base of Rockford Shales, Hackberry, 
owa 
Holopea tenuicarinata, n. sp.—Shell thick, small, sub-coniform ; 
spire rather rapidly tapering; volutions four, convex, flattened 
above; the body whorl ventricose, rounded, nearly or quite equal 
in height to all of the others; slightly produced in front. Exact 
form of the aperture unknown, but judging from the portion which 
remains unbroken, it was subovate in outline; the portion of the 
outer lip which remains is thick. Suture sublinear above, and 
slightly channeled below. Surface ornamented by rather obscure, 
oblique, curved lines. 
imensions : height, 2 mm. ; greatest width, 1 mm. 
i Position and locality: base of Rockford Shales, Hackberry, 
owa. 
Cyclonema brevilineata, n. sp.—Shell turbonate; rather thin ; 
Spire strongly depressed, conical; volutions three, increasing quite 
rapidly in size; those of the spire convex, rounded ; last one large, 
Somewhat more broadly rounded than the upper ones; upper sur- 
face very slightly flattened ; suture well defined below, but not so 
distinctly defined above. Aperture ovate to sub-circnlar. Sur- 
face of hody whorl marked by strong revolving lines or ridges, 
Which become obsolete (except in the case of one specimen) on the 
second volution ; interstices about equal to the width of the revoly- 
ing ridges ; surface of the upper volutions smooth. The revolving 
lines on the first turn show, under a strong magnifier, a more or 
less strong crenate character, though not caused by lines of growth. 
Dimensions: greatest width, 14 mm. ; vertical height, 1 mm. 
