wHfTEAvEs ] LARAMIE AND CRETACEOUS INVERTEBRATA. 19 



almost circular but shallowly emarginate on the columellar side by 

 the encroachment of part of the last whorl but one : outer lip thin and 

 simple. 



Sm-face marked with fine transverse striations. 



Greatest breadth of the largest specimen collected, thirteen millime- 

 tres : height of the same, five mm. ; width of umbilicus of do., about 

 four mm. and a half. 



Old ^lan Eiver, twelve miles below Fort MacLeod (two large 

 specimens) and two miles above Eye-Grass flat, (five smaller ones) all 

 collected by G. M. Dawson, in 1881, from the St. Mary E. Series. 

 As already remarked on page 2, two specimens of this species were 

 collected by E. G. McConnell in 1881, from the " Willow Creek Series " 

 on the Belly Eiver, seven miles above the mouth of the Old Man E. 



There are so many points of resemblance between this species and the 

 next that it is perhaps doubtful whether the shells described above are 

 correctly referred to the genus Patula. They may be immature indi- 

 viduals of a new species of Anchistoma. In Dr. G. M. Dawson's report 

 on the geology of the Bow and Belly Eiver district, they are indicated 

 under the name Selenites, liy the present writer, on account of their 

 supposed resemblance to the recent Sdenites concavus, which is the 

 Helix concava of Say. 



Anchistoma paryclum. (S. Sp.^ 



Shell very small, subdiscoidal, nearly flat above and rather strongly 

 convex below : volutions six, very slender, narrow and coiled on nearly 

 the same plane, increasing very slowly in size and so closely embra- 

 cing that the upper surfaces only of those of the spire are visible : first, 

 second and third volutions about as much elevated as the outer whorl, 

 the foiu-th and part of the fifth sunk to a slightly lower level : sutm-e 

 narrow, not very distinct : outer whorl flattened above and subangular 

 at the periphery : umbilicus small hut deep, about one-third or a little 

 less than one-third of the entire basal diameter. Aperture exceedingly 

 narrow and contracted, its outer margin, as viewed laterally, produced 

 above into a small and narrowly rounded lobe next to the suture, and 

 obliquely truncated below the middle, with an oblique constriction or 

 narrow gi'oove immediately behind the truncated portion. (Jharacters 

 of the interior of the aperture unknown. 



Surface apparently almost smooth, but the surface markings are not 

 well preserved. 



