GASTROPODA. 867 
Protowarthia.] 
in casts; sides gently convex to the edge of the umbilicus into which they descend 
at first rather abruptly, then gently, the ventral part spreading saddle-like over the 
inner volution. Aperture subcordate, notched below; outer lip rather broadly and 
deeply emarginated. Umbilicus about 3.5 mm. wide in a specimen 8 mm. in 
diameter, narrowly rounded at the edge. Surface of casts with distinct, subregular, 
retrally curved, transverse striz, averaging about five in 2 mm. on the sides and 
back. The striz continue over and are quite distinct and curved on the flattened 
dorsum or slit-band. On the latter some very fine revolving lines are faintly dis- 
tinguishable. Somewhat oblique and stronger revolving lines, about four in 1 mm., 
occur on the sides of the volutions. Greatest diameter of a large specimen 8.3 mm; 
width of aperture 5.0 mm.; hight of same 5.0 mm. 
The original description and figures are incorrect where they differ from the 
present work on the species. It is scarcely necessary to go into details. 
Of American fossils we can compare this pretty shell only with species of 
Cyrtolites and possibly of Bucania. Cyrtolites retrorsus and C. carinatus are found with 
it, but both have more volutions, are sharply keeled and without a slit-band. The new 
Cyrtolites parvus is also associated and, because of its small size and relatively coarse 
markings, is more likely than any other fossil known to us to be confused with C. 
nitidula; still, they may be readily distinguished, C. parvus having the usual sharp 
dorsum and wider subquadrate aperture. Besides, it should be borne in mind that 
they are testiferous specimens and not casts of the interior of the species of 
Cyrtolites mentioned that look like casts of Cyrtolitina nitidula. Casts of Cyrtolites 
never show an imprint of the surface ornamentation, but those of the Cyrtolitina, on 
the contrary, are very distinctly marked. 
Formation and locality.—Upper part of the Trenton group, in the river quarries ust west of Cov- 
ington, Kentucky. 
Collection.—E. O. Ulrich. 
Genus PROTOWARTHIA, n. gen. 
Bellerophon (part.), of numerous authors. + 
For generic characters see page 848. 
The, chiefly Lower Silurian, group of shells for which this genus is proposed is 
strikingly similar to the Permo-Carboniferous species embraced in Waagen’s genus 
Warthia. Indeed, there is little more than a single character, and that possibly is 
not always well developed, which distinguishes them. In Protowarthia, namely, the 
inner lip is prolonged as a thin grano-lineate sheet around the umbilical regions 
and over a greater or lesser portion of the dorsum of the posterior end of the last 
volution. Nothing of this kind has been observed in Warthia. That the surface of 
