28 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 77 



the left shoulder and lateral to the third transverse ring in the 

 Palaeoscincus skeleton (pi. 6, fig. 1). Viewed from below the base 

 of this scute is subrectangular in outline, having a greatest length 

 of 350 millimeters, and a width at the center of 120 millimeters. 

 This surface is traversed by a median longitudinal depression that 

 gradually deepens toward the spinous end. The base is concave from 

 end to end with a torqued posterior end. The shape of the basal 

 surface is probably an adaptation in better conformation with the 

 underlying bones of the shoulder region. Its depth of insertion in 

 the skin is clearly indicated by a rugosely roughened band that 

 extends entirely around the basal portion of the scute. On the dorsal 

 surface is a high, sharp edged keel that has its origin on the posterior 

 internal angle and extends diagonally across the scute. This keel 

 gradually increases in height from its point of origin terminating 

 in a high, sharply-pointed but compressed spine that strongly over- 

 hangs the posterior basal part of the scute. Measured from the 

 base to the tip this spine is 242 millimeters long. 



A dermal plate illustrated by Lambe ^^ and provisionally associ- 

 ated with Euoplocephalus tutus, may, on account of its close 

 resemblance to the plate just described, be quite certainly referred to 

 the genus Palaeoscincus. 



A pair of large triangular shaped, sharply pointed spines, each 

 coossified with a smaller scute carrying a very much smaller and 

 blunter spine undoubtedly represent the next two spines of the 

 lateral series which project outward from the side of the body 

 above the fore leg. In Palaeoscincus, however, these two elements 

 appear to remain distinct. These coossified plates have a greatest 

 basal length of 460 millimeters. The taller spine measures 400 

 millimeters in height, the shorter only 180 millimeters. These 

 spines are figured in Plate 6, Figure 4. 



Among the dermal elements there are three other scutes which 

 may be classified as spines but no clue has yet been obtained as to 

 their position. These are of much smaller size than those previously 

 described and one is shown in Plate 6, Figure 2. These have sub- 

 ovate, concavely excavated bases, low asymmetrically placed keels, 

 that pass into two obtusely pointed compressed or angularly rounded 

 spines that project backward at a low angle. Two of these are the 

 right and left elements of a pair. 



The position of this lateral row of spined dermal elements in the 

 Palaeoscincus, skeleton (pi. 8), having the spines projecting out- 

 ward and forward seems entirely opposed to a natural placing. In 

 such a position they would have been a source of constant annoyance 

 and trouble to the animal by constantly catching on small trees 



-5 CoDtrib. Canadian Paleont., vol. 3, 1902, p. 57, fig. 1.3. 



