866 THE PALEONTOLOGY OF MINNESOTA. 
[Oyrtolitina. 
the type of a new genus intermediate in position between Carinaropsis and 
Cyrtolites. : 
Formation and locality——Ctenodonta bed of the Black River group, Goodhue county, Minnesota 
The Wisconsin specimen seems to be from an equivalent horizon at Beloit. 
Collections.—University of Wisconsin; E. O. Ulrich. 
Genus CYRTOLITINA, n. gen. 
Cyrtolites (part.), ULRICH, 1879, Jour. Cin. Soc. Nat. Hist., vol. ii, p. 12. LrNpsTrom, 1884, Silurian 
Gastropoda of Gotland, pp. 82-84. 
For generic characters see page 847. 
The five species at present believed to have the characters of this genus were 
originally all referred to Cyrtolites. They are, however, quite distinct from the 
typical species (ornatus) of that genus, and, in certain respects at least, nearer to 
Bucania and Conradella. With the latter genera they agree in the surface sculpture, 
in having the aperture distinctly emarginated, and in possessing a slit-band, while 
they differ in these features from Cyrtolites. On the other hand the agreement with 
Cyrtolites is stronger only in the form of the volutions and in their number, the 
whorls being much less in number and higher than wide instead of the reverse as in 
Bucania. Tt is difficult to decide as to the relative merits of these agreements, and, 
as we are scarcely beyond the threshold of knowledge respecting the Paleozoic 
Gastropoda, we will not presume to attempt it. Still, while we pay tribute to 
prevailing opinions in both the selection of the new name and in referring the genus 
to the Cyrtolitide, it is to be understood that the arrangement is less in accordance 
with our views than if we had placed it among the Bucaniide. To this statement 
we may add the suggestion that Cyrtolitina may have been derived from some form 
of Bucania like B. subangulata. 
Comparing Cyrtolitina with its possible relatives we find that it differs from 
Cyrtolites in having a slit-band, less carinate dorsum, an apertural emargination, 
higher (more compressed) volutions, and surface markings that are to be called lamel- 
lose rather than reticulated; from Bucania in having fewer and laterally instead of 
vertically compressed volutions; and from Conradella in having fewer and more 
rapidly enlarging volutions, much shorter apertural slit, no distinct dorsal keel, and 
the subimbricating surface lamellz curved strongly backward on the dorsum. 
CyrToLitina niTrDULA Ulrich. 
PLATE LXII, FIGS. 53—55. 
Oyrtolites nitidulus ULricu, 1879, Jour. Cin. Soc. Nat. Hist., vol. ii, p. 12. 
Shell small, 6 to 8 mm. in diameter; volutions about two, rapidly increasing in 
size, the outer embracing quite a half of the inner; dorsum blunt, thick, flattened 
