1012 THE PALEONTOLOGY OF MINNESOTA. 
(Seelya mundula. 
founded on an interior cast of a rather slender shell of this genus. It is from the 
Point Lévis limestone of the Quebec group. We know of no species in the Trenton, 
and the Cincinnati species about to be described is a very modest representative. 
There are at least two Upper Silurian species. One of these occurs in the Niagara 
limestone at Chicago, and was described by Meek and Worthen as Plewrotomaria 
cyclonemoides. The other is the well known Pleurotomaria lloydii of Sowerby, 
occurring in England and Gotland. Several good varieties or closely related species 
are included in the European species, and one, as figured by Lindstrém, greatly 
resembles our S. ventricosa. 
SEELYA MuNDULA, n. sp. (Ulrich.) 
PLATE LXX, FIGS, 11-12, 
Hight and width nearly equal, 10 to 13 mm.; apical angle 70° to 75°; volutions four, subangu- 
lar; band prominent, narrow, concave; upper side of whorls with a strong angulation or carina midway 
between the band and the suture, and sometimes with a small ridge close to the suture, the intermediate 
spaces more or less concave; lower side convex except immediately beneath the salient band, with two or 
three (perhaps more) small revolving ridges ; umbilical perforation very minute; aperture rounded, lines ~ 
of growth obscure. 
Remembering that the band is concave, we know of no shell in the Trenton and Cincinnati or Hud- 
son River periods that might be confounded with this species. 
Formation and locality.—Lower part of Lorraine group, Cincinnati, Ohio, and Newport, Kentucky. 
Good specimens appear to be very rare. 
Collection.—E. O. Ulrich. 
Genus HORMOTOMA, Salter. 
Murchisonia (part.) of authors. 
Hormotoma, SALTER (as subgenus of Murchisonia, D’Arch. and Vern.), 1859, Can. Org. Remains, 
Decade 1, p. 18; G/HLERT, 1887, Extr. Bull. Soc, d’Etud. Sci. d’Angers, p. 18. 
Goniostropha (part.), GUHLERT, op. cit., p. 13. 
For generic characters see page 959. 
This division of the Pleurotomariide seems to us as in every way fully deserving 
the rank of a distinct genus. In the first place, the species of Hormotoma have no 
discoverable relation to the original types of Murchisonia, the genus with which 
they have been heretofore almost-universally associated. Next, the generic type 
maintained its peculiarities through a long period of time, beginning no later than 
the Calciferous and extending upward through the intervening beds to the top of 
the Upper Silurian. Beyond this horizon we meet with slightly modified but 
undeniable descendants in the lower and middle divisions of the Devonian system. 
The latter, because they have developed a short apertural slit, should perhaps be 
separated, in which case the somewhat inappropriate term Goniostropha might be 
