IttilLIBRARY' 



THE OTTAWA NATURALIST. 



Vol. XVI II. OTTAWA, JULY, 1904. No. 4 



ON THE SQUAMOSO PARIETAL CREST OF TWO 



SPECIES OF HORNED DINOSAURS FROM THE 



CRETACEOUS OF ALBERTA 



By Lawrence ;\I. Lambe, F.G.S., F.R.S.C, (With two plates.) 



One of the most interesting^ features of the fauna of the Belly 

 River series of the Cretaceous of the West is the presence of Cera- 

 topsids more primitive than those of the Laramie. Of the former 

 the writer, in the second part of volume III (quarto) of Contribu- 

 tions to Canadian Paleontology, 1892, described three species of 

 Monoclonius^ viz. M. da^vsoui, M. canadensis and M. belli, all from 

 the Red Deer river district. In a further study of the type material 

 on which M. daivsoni was founded, it became apparent that two 

 species had been included under one name and also that the 

 spe ies distinct from M. daivsoni probably represents a new 

 generic form. The material denoting- the new genus and species, 

 and originally referred 10 M. daivsoni, consists of a large posterior 

 crest (p. 59, fig. 15, op. cit ), with which was found a nasal horn 

 core. This crest is unique in having hooked-processes developed 

 on the posterior border. 



For the form represented by the crest with hooked-processes 

 the generic term Centrosaiirus is proposed and the na.me apertns, in 

 reference to the large fontanelles, is deemed an appropriate one 

 for the species. 



In a paper by the writer, to be published shortly, a detailed 

 description with figures will be given of the posterior crest of 

 Centrosaiirus apertiis as well as oi that of Monocloniiis canadensis. 

 The skull, described in the above mentioned memoir, p. 57, lig. 

 14, cat. No. 1 1 73, is retained as the type of Moiioclonius daivsoni. 



