42 THE ROYAL SOCIETY OF CANADA 



Measurements of Maxillary Tooth of Type. 



mm. 



External depth of crown, including cingulum 7.5 



Internal depth of crown, including cingulum 6.0 



External depth of blade (crown below cingulum) 5.5 



Internal depth of blade (crown below cingulum) 4.5 



Maximum breadth of crown (at cingulum) 7.0 



Maximum thickness of crown (at cingulum) 4.5 



Breadth of root 4.0 



Thickness of same 3.0 



The teeth of Panoplosaurus have the general characteristics of 

 those of the known North American genera of armoured dinosaurs, in 

 all of which the pointed crown is laterally compressed, has denticulated 

 borders and a basal cingulum, and is borne on a long, more or less 

 cylindrical root. This style of tooth is found in Stegosaurus and 

 Ankylosaurus. Palaeoscincus is known only from teeth of this general 

 shape. The teeth of Euoplocephalus have not been certainly recog- 

 nized but they are no doubt represented by one of the different pat- 

 terns of the numerous stegosauroid teeth found loose in the Belly 

 River formation of Alberta. 



In comparison with the teeth of Stegosaurus those of Panoplos- 

 aurus are larger, are proportionately higher in the crown, have a thin- 

 ner blade, and a more pronounced cingulum, particularly on the outer 

 side, and the denticles, although of about the same number are rather 

 less conspicuous. Compared with Ankylosaurus they are of much the 

 samç size, but the crown is lower, with fewer denticles, and is externally 

 concave with a very pronounced cingulum, whereas in Ankylosaurus 

 it is strongly convex on the outer side and the cingulum is here absent. 



The teeth of Palaeosciticus, although of the general stegosauroid 

 pattern, differ in many particulars from those of both Panoplosaurus 

 and Ankylosaurus. They are usually much larger, with a low crown 

 and coarse denticulations, and can readily be distinguished at a 

 glance. This is the most common form of tooth of the armoured 

 dinosaurs of the Belly River formation and is found in large numbers 

 on weathered rock surfaces. It is hoped that the teeth of Palaeoscincus 

 as well as those of Troodon will be found in association with the skull 

 at no distant date. Here may be mentioned Palaeoscincus asper of 

 Belly River age, represented at present only by a tooth, with strongly- 

 marked characters, described by the writer in 1902."^ 



Armature of the Neck and Trunk (Plates IX, X and XII). The 

 protective covering of the body is different from that of the head in 

 that it consists of integumental scutes, mostly distinct from each 



' op. cit. 



