44 



NEW REPTILES AND STEGOCEPHALIANS FROM 



edges. The low knob is nearer to the posterior corner of the plate (fig. 16 a). The 

 anterior edge is the broader and the outer edge slopes backward and inward to the pos- 

 terior edge. The left plate of the outer row of this series is nearly complete. The 

 inner edge is thickened to form a firm union with the inner plate; the outer edge is thinner 

 and slopes backward and outward to the broader posterior edge. The spine is located 

 on the outer half of the plate and is incUned outward and sUghtly backward. The 

 anterior surface of the spine is drawn out into a narrow, sharp edge which slopes forward 

 to the middle of the plate. 



Fig. 16. — Desmatosvdius spurensis, dorsal armor of. All figures X 0.3. 



A. Upper view of median plate of second series, right side. 



B. Upper view of median plate of the third series, left side. 



C. Upper view of the two median plates of the fifth series. 



D. Anterior view of the right side of C. 



E. Inner (upper) view of the lateral plate of the third series, left side. 



F. Posterior view of E. 



The third series has the plates (fig. 16 b) nearly complete. The median plates 

 are similar to the second, except that they are proportionately larger. It is clear in this 

 series that the plates overlap to the rear, and this is continuous throughout the series. 

 There is little, or a very fine, sculpture. The outer plates have high spines located 

 near the posterior edge, with a thin flange extending down the anterior side. This is 

 shown in figure 16 A and b. The two parts of each plate lie nearly at right angles 

 to each other. The inner edge is thickened for articulation with the median plate, 

 while the outer part is thin and larger. The anterior edge is narrower, but the outer 

 edge slopes backward and outward to meet the broader posterior edge. The outer side 

 shows the beginning of a rough sculpture of relatively small pits and ridges. When 

 in position the spines point outward and a little upward. 



The fourth series is represented by the conjoined plates of the left side and an 

 imperfect median plate of the right side. The left plates are complete, 'except for the 

 extremity of the spine. The median plates are similar to those preceding, but are 

 larger. The outer plate carries a heavy spine, of which the lower half only is preserved. 

 The inner side of the spine is nearly flat, but there is a thin, strong ridge on the anterior 

 side. As in the preceding plates, the anterior edge is shorter than the posterior, and the 

 outer edge slopes backward and outward. Both the inner and the outer plates show an 

 increase in the size of the sculpture, which becomes so heavy and rough in the dorsal 

 region. 



