500 GEOLOGICAL SURVEY OF THE TERRITORIES. 



crowded zigzag verti cal bands of brown and light yellowisli colors; lines 

 of growth moderately distinct. 



Height of a nearly medium-sized specimen, 0.40 inch ; breadth, 0.43 

 inch. Some examples are as much as twice these dimensions. 



Although the specimens show the pattern, or style, of the original 

 coloration of this shell quite distinctly, the colors themselves may, 

 of course, have been different on the living shell. Usually the zigzag 

 markings are quite distinct on the specimens as found, but on some ex- 

 amples the bands are blended and become fainter, so that the surface 

 merely presents a light brownish tinge. It is always polished, however, 

 on all the specimens seen. 



This species seems to be more nearly allied to N. Nebrascensis^ M. & H., 

 from Jurassic beds near the head of Wind Eiver, than to any other form 

 with which I am acquainted. It may be readily distinguished, however, 

 by its more depressed spire and the slight ilattening of its volutions 

 above, as well as by its more flattened and more concave inner lip. It 

 likewise attained a larger size than any of the specimens of that species 

 1 have seen. It is one of the most abundant shells observed at the 

 locality, and is usually found in a better state of preservation than any 

 of its associates. 



The specific name is given in honor of Dr. Henry M. Bannister, of the 

 Smithsonian Institution, to whom I am under obligations for valuable 

 assistance while visiting the Eocky Mountain region during the past 

 summer. 



Locality and position. — CarJeton's coal-mine, Coalville, Utah. 



IsIeritina (Neritella) pisum, Meek. 



Shell globose; spire much depressed; volutions about thr,ee, rapidly 

 increasing in size, so that the last or body turn (which is a little de- 

 pressed above) comi:)oses nearly the entire shell; inner lip broad, flat- 

 tened, and smooth; aperture small and semicircular; surface nearly or 

 quite smooth. 



Height, 0.22 inch ; breadth, 0.26 inch. 



This little shell has much the form of the last, and I was at first inclined 

 to think it might be the same, notwithstanding its much lower position 

 in'the series. A careful comparison, however, shows that it has a de- 

 cidedly broader, flatter, and straighter inner lip, while its aperture is 

 prof)ortionally smaller, and quite different in form. 



Locality and position. — Coalville, Utah. Cretaceous, from below the 

 lower bed of coal. 



Neritina pisiformis. Meek. 



Shell small, sub globose, or obliquely rhombic, the height being slightly 

 less than the oblique breadth ; spire rather prominent for a species of 

 this genus ; volutions three to three and a half; convex ; last one large, 

 and forming most of the bulk of the shell; aperture subovate, consider- 

 ably contracted by the flattened, moderately wide inner lip, which is 

 nearly straight on its inner margin, and provided there with four small 

 denticles, the upper one of which is largest. Surface smooth. 



Height, 0.30 inch ; greatest oblique breadth, 0.32 inch. 



This little shell agrees so nearly in size and form with the described 

 species, {^. pisum,) that they may be readily confounded, as they are 

 found with the aperture filled with rock. A fortunate fracture of one 

 of the specimens exposed the inner edge of its flattened columella, how- 



