96 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



examples tbe revolving lines are absent, or nearly so, and the color- 

 markings are less distinctly zigzag in their direction. 



Axial length, 10 millimeters; transverse diameter, 13 millimeters. 



The specific name is given in honor of Mr. Lawrence Bruner, who first 

 discovered the species. It differs from N. volvilhieata White, in being 

 somewhat more globose, having a less elevated spire, and the inner lips 

 broader and less retreating. It is marked by revolving lines, somewhat 

 like that species, but they are sometimes obsolete. It is also orna- 

 mented by zigzag color-markings. The type specimen is represented 

 by figs. 7 and 8 on Plate IV. 



Associated with the foregoing is still another form, much smaller, 

 which seems to be the young of ])f. volvilincata. It is without color- 

 markings, and the inner border of the inner lip is dentate. 



Position and locality. — Laramie Group; valley of South Platte Eiver, 

 Northeastern Colorado, where it is associated with the two last- described 

 species. 



Genus MELAXOPSIS Lamarck. 



Melanopsis americana (sp. uov. ), Plate IV, figs. 9 and 10. 



Shell very small, sides straight, and meeting at the apex at an acute 

 angle; volutions .six or seven, those of the spire not convex, but so flat- 

 tened as to show only a linear suture between them, which is somewhat 

 irregular; proximal portion of the last volution gently convex, its length 

 being more than half che entire length of the shell; outer lip thin, not 

 expanded, its margin not distinctly sinuous; inner lip having a very 

 strong callus nearly filling the distal end of the aperture, leaving a 

 narrow groove between it and the margin of the outer lip, and grad- 

 ually diminishing in thickness towards the proximal end of the aper- 

 ture; aperture, as bounded by the outer lip and callous inner lip, rudely 

 subelliptical, angular at its distal end, rounded at its ])roxiinal end, and 

 terminating at the end of the columella in a distinct, narrow canal, 

 which is slightly bent to the left. Surface marked only by faint lines 

 of growth. 



Length, 7 millimeters; diameter of last volution, 3h millimeters. 

 (Museum No. 11559.) 



If we except the species wliich were published by Conrad under the 

 generic name of BuUio2)sis, but which probably belong to the genus 

 Melanopsis., no species of the latter genus have hitherto been known in 

 North America, either fossil or living. Tbe s])ecies which is here de- 

 scribed is plainly congeneric with the living Melanopsis costcllata Fe- 

 russac, and with the Eocene M. buccinoidea Ferussac, both of Western 

 Europe. 



Position and locitlity.—haY-dmie Group, Valley of South Platte Eiver, 

 Northeastern Colorado, where it is associated with the three last de- 

 scribed forms, and also with Corbtfla, Melunia, Anomia, and Osirea. 



