white.] FOSSILS OF THE FOX HILLS GROUP. 183 



Fossil Ridge, where I discovered it; which, strata, although hot sepa- 

 rable froin the Fox Hills Group iu Colorado, are uo doubt equivalent 

 with those of the Fort Fierre Group in the Upper Missouri Fiver region. 

 I obtained it in considerable numbers from the higher strata of the Fox 

 Hills Group at the mouth of the Saint Vrains and in the valleys of the 

 Cache a la Poudre and Little Thompson Creek. Some well preserved 

 pieces of the test of this species obtained at Fossil Eidge show that 

 what appear to be nodes between the ribs in certain specimens are in 

 the unchanged shell really holes through its substance. The pieces 

 referred to were found to break along the line of these holes, just as post- 

 age-stamps separate along the hues of holes made for that purpose. In 

 other examples from the valley of the Cache a la Poudre I found the 

 appearance of nodes in the place of the holes, just as described by Mr. 

 Meek ; but careful examination showed that the supposed nodes consist 

 of the stony filling of the holes in the test, which, being harder, had 

 withstood subsequent weathering better than the test itself. It is pos- 

 sible, however, that the outer end of these holes was covered with a 

 shelly layer ; but it must have been only a film at most, for I could dis- 

 cover nothing of the kind in the narrow grooves between the ribs of the 

 specimens referred to, AYhich seemed to be perfectly preserved. 



19. Protocardia subquadrata Evans & Shumard sp. 



Dr. Evans first discovered this species in the Fox Hills Group of the 

 Upper Missouri Eiver region. I obtained it in the valley of the Little 

 Thompson; and I have also recognized it in some collec J *ons made by 

 Mr. W. H. Holmes at the mouth of the Saint Trains. It seems never 

 to have been discovered in the Fort Pierre Group of the Upper Mis- 

 souri. 



20. Protocardia rara Evans & Shumard. 



Associated with the foregoing in the valley of the Little Thompson, I 

 found some small shells that seem to belong to this species, but their 

 identification was not quite satisfactory. 



21. Callista deiceyi Meek & Hayden. 



A few imperfect examples, found both at Fossil Eidge and in the val- 

 ley of Little Thompson Creek, evidently belong to the JDosinopsis section 

 of this genus. They are too imperfect for certain specific determination, 

 but the character of the internal cast and what remains of the shell in- 

 dicates a proper reference to G. deweyi. 



22. Tellina scitula Meek & Hayden. 



This is a very common and widely distributed Cretaceous species, being 

 found on both sides of the Eocky Mountains. It seems, however, to be 

 confined everywhere to the strata of the Fox Hills Group. Iu this dis- 

 trict I obtained it only from the upper strata of that group, and only at 

 the mouth of the Saint Vrains and in the valley of the Cache a la Pou- 

 dre. 



23. Tellina equilateralis Meek & Hayden. 



A single valve of a species, apparently the T. equilateralis of Meek and . 

 Hayden, was found at the mouth of the Saint Vrains. The original ex- 

 amples were found in the uppermost of the Fox Hills layers at the mouth . 

 of Judith Eiver on the Upper Missouri. Meek referred the species to. • 

 Tellina from external characters only, and there are reasons for believ- 

 ing that it does not properly belong to that genus. 



