•«HiTEAVEs.] LARAMIE AND CRETACEOUS INVERTEBRATA. 23 



Two miles above Eye-Grass flat and twelve miles below Fort 

 MacLeod on the Old Man Eiver ; also Gooseberry Canon on the St. 

 Mary Eiver; G. M. Dawson, 1881. Pincher Creek, T. C. Weston, 

 1883. All from the St. Mary E. Series. 



The specimens from the Bow Eiver, which are here regarded as pro- 

 bably representing the most typical form of G. tenuicarinata, have con- 

 vex and scarcely angulated whorls, the later ones of the spire being 

 encircled with three or fom- rather distant, spiral raised lines, and the 

 -outer whorl by six or seven. Under a lens also, the sm-face of the 

 volutions in this form is seen to be marked by crowded and minute 

 ■transverse raised lines, at right angles to the spiral ones. 



The shells from the localities indicated above seem to form a well- 

 marked variety of G. tenuicarinata, which differs from the Bow Eiver 

 and more typical form in having the whorls always rather distinctly 

 angulated above the middle, in the fact that the spiral raised lines are 

 obsolete except the single raised line or minute keel upon the angle, 

 and in the minute sculpture, which consists of exceedingly fine revolv- 

 ing impressed lines, instead of transverse raised stria3. 



Htdrobia. 



A number of minute and slender fossil shells which appear to belong 

 ■either to this or to some closely allied genus, were collected by G. 31. 

 Dawson at the North or Second Branch of the Milk Eiver in 1874 and 

 1881; on the Old 3Ian Eiver, two miles above Eye-Grass flat, in ISSl; 

 and by Mr. T. C. Weston at Pincher Creek, in 1883 ; from the St. Mary 

 E. Series. They rarely exceed three millimetres in length, and 

 most of them are mere casts of the interior of the shell, though in some 

 specimens the whole or part of the inner layer of the test is preserved. 

 Some of them are considerably elongated and narrow in proportion to 

 their length, and such specimens appear to be rather nearly related to 

 the Hydrohia recta of White, though they are not quite so slender. 

 Others again are comparatively shorter and more conical, and these 

 are difllcult to separate from the H. Vtahenais of White and similar 

 "forms, but the whole of the specimens are too imperfectly preserved to 

 be satisfactorily determined, and it is doabtfiil even how many species 

 they represent. 



