1 89fi.] Laramie Mammals and Horned Dinosaurs. 1 1 7 



marine beds which contain invertebrate fossils characteristic 

 of the Fox Hills deposits, may well be questioned, especially if 

 we exclude from the Ceratops beds the Judith Riverbeds and 

 refer them to a lower horizon, retaining for them the name 

 ,hi>! it), Hirer beds. At no place in the Converse Co. region <lo 

 the true Ceratops beds, with remains of horned dinosaurs, rest 

 upon true marine Fox Hills sediments; nor arc the < 'era tops 

 beds in this region overlaid by strata which could he referred 

 without doubt to the Laramie. The writer has, in a paper 

 published in the American Journal of Science of February. IMC!, 

 stated that the Ceratops beds rest directly upon the Fox Hills 

 series, and has provisionally referred the very similar series 

 of sandstones and shales conformably overlying the Ccmfo^s 

 beds to the upper Laramie ; but it would doubtless be better to 

 restrict the limits of the Ceratops beds to those strata in which 

 horned dinosaurs occur, and to consider the underlying 400 

 feet of barren sandstones as the equivalent of the Judith Rim- 

 beds. Future investigations will doubtless show that the sand- 

 stones, shales and lignites overlying the typical Ceratops beds 

 in Converse Co. should be referred to the Fort Union beds and 

 not to the Laramie, as, according to Knowlton, the limited flora 

 sent him now indicates. 



The terms Fox Hills and Laramie a.- now used cannot he 

 taken to represent distinct and different periods of time, for as 

 has been shown by G. M. Dawson, Selwyn and McConnell in 

 the Belly River region in Canada, and frequently observed by 

 the writer on the upper Missouri in Montana, marine beds 

 with typical Fox Hills fossils have been found interstratifr d 

 with fresh and brackish water beds containing characteristic 

 Laramie fossils, showing conclusively that the two periods were 

 in part at least contemporaneous ; the one representing the 

 marine and the other fresh or brackish water forms existing at 

 the same time and in not widely separated regions, these alter- 

 nations in the nature of the fauna in the same locality having 

 been brought about by successive encroachments and reces- 

 sions of the sea. It is not at all impossible that in the region 

 of Converse Co., Wyoming, marine conditions prevailed con- 

 tinuously until late in Laramie times, and that during the 



