INVERTEBRATE PALEONTOLOGY. 541 



lines of growth; aperture apparently rather narrow; columella twisted so as 

 apparently to form a moderately distinct fold below. 



Length, aboul 1.16 inches; breadth, near 0.53 inch. 



I have seen but a single specimen of this shell which unfortunately has 

 most of the outer lip broken away, and the columella not well exposed. Its 

 surface is also somewhat worn, so that it is possible that the description may 

 require some modifications when better specimens are obtained. There can, 

 however, be no difficulty in distinguishing it from all of the other shells yet 

 known in these rocks. 



It is evidently related to several elongated species figured by M. Math- 

 eron from the Lignite Tertiary formations of the southeast of France (Cat. 

 Method., pi. o(i), being apparently most nearly like his P. Gardanensis, but 

 differing in having a proportionally narrower body-whorl and a more faintly- 

 impressed suture. It seems to have a rather more prominent fold on the 

 columella than is common in this genus.* 



Locality and position. — Judith River group, at the mouth of Judith 

 River, on the Missouri, in Montana; probably belonging to the closing part 

 of the Cretaceous period. 



is ii 1 3 ii ii *. longiusculus, M. & H. 



Plate 43, figs. l(i, «, h. 



Flti/sci longiiiseiila, Meek and Hayden (1856), Proceed. Acad. Nat. Sci. Philad., VIII, 119. 

 I'hysa (Aplexa) longiuscula, Meek and Hayden (I860), ib., 4:51. 



Shell narrow-subovate ; spire rather elevated, pointed at the apex ; volu- 

 tions six to six and a half, nearly flat or slightly convex ; suture distinct, 

 though not deep; surface marked by rather obscure lines of growth ; aper- 

 ture apparently narrow-subovate, acutely angular above, and narrowly rounded 

 below. 



Length, about 0.56 inch ; breadth, near, 0.27 inch ; apical angle nearly 

 regular, divergence about 0.47°. 



Our specimens of this species are more or less compressed, and have the 

 aperture distorted, so that I am not able to characterize it as fully as might 

 be desired. The aperture seems to be quite narrow, and the body-whorl 



* This species agrees in size and pretty nearly in form with one I have described from the Ter- 

 tiary of Wyoming, under the name Physa Bridgerensis (more properly Bulinus Bridgerensis), in Hayden's 

 Report of the United States Geological Survey of the Territories for 1872, page 516. Still it has a less 

 ventricose body-volution, and a more pointed spire, as well as more flattened upper volutions. 



