1910] The Ottawa Naturalist. 151 



as a spine for defensive purposes it would have projected freely 

 above the crest. Centrosaurus and Monoclonius are regarded as 

 antecedent to forms in which the size of the fontanelles is much 

 reduced, culminating in Triceratops with an entire frill. We 

 could scarcely, however, consider the spur of bone crossing the 

 fontanelle a little above its general plane, as an attempt on the 

 part of Centrosaurus to reduce the size of the opening, although 

 if we accept a Monoclonius-Triceratops phyllum as one of the 

 two lines of descent in the Ceratopsia,* we would expect a strong 

 tendency to close the parietal fontanelles in both Monoclonius 

 and Centrosaurus. The presence of the outgrowth on one side 

 of the crest only, further inclines one to the belief that this spur 

 has no morphological significance, but has been induced rather 

 by an inherent tendency on the part of the species to add to the 

 defensive armature in this part of the skeleton. 



The figure here given is from the drawing reproduced in 

 plate 1, Transactions Royal Society of Canada, vol. X, 1904, 

 in the writer's paper "On the squamoso-parietal crest of the 

 horned dinosaurs Centrosaurus apertus and Monoclonius cana- 

 densis from the Cretaceous of Alberta," to which is added the 

 outgrowth from the posterior bar in its true position, the original 

 drawing for figure 3 of the above plate being used; one-sixth 

 natural size; a, squamosal suture; b, post-frontal suture; g, 

 groove passing beneath base of bony outgrowth. 



The generic name Euoplocephalus proposed in place of 

 Stereocephalus (preoccupied). 



In 1902 the writer described a new genus and species of 

 herbivorous dinosaur from the Judith River (Belly River) beds 

 of Red Deer river, Alberta, under the name Stereocephalus 

 tutus (Contributions to Canadian Palaeontology, vol. III. [quarto], 

 part II., p. 55). As the term Stereocephalus has been already 

 used for a genus of insects it is necessary to suggest another 

 generic name for the species from Red Deer river represented 

 by the upper part of a heavily armoured cranium and a trans- 

 verse, semicircular series of five keeled scutes from the neck or 

 tail. Euoplocephalus (Gr., euoplos, well armed, and kephale, 

 head) is therefore now proposed as an appropriate name for the 

 genus to take the place of Stereocephalus as applied to the 

 Cretaceous stegosaur S. tutus. 



Monographs of the United States Geological Survey, vol. XLIX 

 The Ceratopsia by John B. Hatcher, based on preliminary studies by 

 O. C. Marsh, edited and completed by R. S. Lull. 



