864 THE PALEONTOLOGY OF MINNESOTA. 
[Cyrtolites parvus. 
CyrToLiTEs PARvVus, n. sp. (Ulrich.) 
PLATE LXII, FIGS. 45 - 47. 
Shell smal!, about 7 mm. in diameter, 6 mm. wide at the aperture, consisting 
of about two rapidly enlarging volutions, subquadrangular in section and somewhat 
wider than high; dorsum carinated, the keel not very prominent, minutely wavy in a 
side view; sides narrowly rounded, scarcely angular; dorsal slopes gently convex, with- 
out undulations except near the aperture where several obscure ones may be noticed. 
Surface with comparatively coarse lines of growth, curving strongly backward from 
the edge of the umbilicus to the dorsal carina which they cross without interruption. 
These lines are connected by more closely arranged and very delicate obliquely 
revolving lines, which, being lower than the transverse set, might easily be 
overlooked. On the last turn seven or eight of the transverse lines occur in 2 mm. 
Considering the size of the shell, the surface markings are stronger than in any 
of the other species of the genus. From C. carinatus Miller, which it resembles 
most, it differs also in having the sides of the volutions narrowly rounded 
instead of sharply angular. In C. retrovsus and C. ornatus the surface ornamen- 
tation is much more distinctly reticulated, and, while the former has a much 
stronger keel and concave dorsal slopes, the latter is especially distinguished 
by the absence of a sinus in the outer lip and consequently in the more strictly 
transverse course of the surface markings. Internal casts of Cyrtolitina nitida 
resemble testiferous examples of this species; but if this fact is borne in mind, and 
further that in the former the back is flattened, the volutions more compressed 
laterally, and the surface markings of the cast thicker and wave-like rather than 
thread-like, it is almost impossible that confusion between them can ever occur. 
Formation and locality. Near top of Trenton group at Covington, Kentucky. 
Collection.—K. O. Ulrich. 
CyRTOLITES DISJUNCTUS, %. Sp. 
PLATE LXII, FIGS. 48 and 49. 
Shell about 24 mm. in hight, consisting of about two entirely free or disjoined 
whorls, coiled very nearly or quite symmetrically; volutions strongly and sharply 
carinated dorsally, the sides somewhat narrowly rounded within the center, and 
strongly undulated transversely; ventral side less convex, with two abruptly 
elevated narrow central carine, forming a groove with raised edges or what is 
commonly called a “saddle”; hight of volutions increasing with age more rapidly 
than the width, the transverse section, excluding the dorsal and ventral carine, 
changing from transversely subelliptical to almost circular at the aperture of a fully 
