WHITEAVES.] LARAMIE AND CRETACEOUS INVERTEBRATA. 55 



D. FEOil THE BELLY RIVER SERIES. 



Dr. Dawson's views on the stratigraphical position of the " Belly 

 River Series " are fully stated in pages llS-126 C, of the Report of 

 Progress of the Canadian Suiwey for 1882-8.3-S4. It is there 

 explained that this name has been used to designate a considerable 

 thickness of beds which occupy a position below the shales of the Fort 

 Pierre Group, or at least below an upper portion of those shales. The 

 beds of the "Belly River Series " are estuarine throughout, and ditfer 

 in this respect from those described as occurring below the shales of 

 the Fort Pierre G-roup in the Missouri region proper. Owing to the 

 diiferences between the section in the Bow and Belly region and that 

 on the Missouri, the exact stratigraphical position of the ''Belly River 

 Series " was for a long time considered doubtful, bat Dr. Dawson has, 

 on stratigraphical grounds, become convinced that it occupies the 

 horizon assigned to it in his report. It may be added that Mr. R. 6. 

 McConnell, who assisted Dr. Dawson in the geological work, fully 

 concui-s in this opinion. 



In the course of the explorations two sets of beds were at first 

 distinguished, and these were pirovisionally recognized as the " pale " 

 and "yellow " series respectively. These have now been united under 

 the name " Belly River Series," the first named being the upper and 

 the second the lower part of the series. It should be stated, however, 

 that while (according to Dr. Dawson) the evidence is indubitable and 

 precise as to the fact of the position of the pale or upper piortion of 

 these shales, that affecting the yellow or lower beds is somewhat less 

 definite. The bearing of all the facts is discussed in the report above 

 cited, and need not be rejDeated.* 



The molluscan fauna of the pale or upper beds is comparatively 

 scanty, though vertebrate remains, which have not yet been reported 

 on, are somewhat abundant. It is unfortunate that the rather exten- 

 sive collection of mollusca made from these beds by Mr. T. C. Weston 

 at a locality in Milk River Ridge which proved unusually rich in 

 fossils, and which was sjjecially revisited in 188.3 for the purpose of 

 collecting them, was subsequently lost in transit. The yellow and 

 supposed lower beds often contain great quantities of molluscan 

 remains, and a number of spjecies are represented. 



* In this connection it seems desirable to state that all the notes on the stratigraphical ijosi- 

 tion and litholotncal peculiarities of the formations mentioned in the pre.«ent paper were supplied 

 by Dr. Gf. M. Dawson. Judging by their respective invertebrate faunte, it would seem impracti- 

 cable to separate the " Belly River Series " from the Laramie and more especially from the 

 " .Judith River Group," on purely palgeontological evidence. (.J. F. W.) 



