[lambe] PANOPLOSAURUS M I RUS 41 



scutes forming a longitudinal dorsal series on the neck. Principal 

 lateral scutes of neck and trunk keeled, in longitudinal rows. Scutes 

 of ventral surface small. Centra of cervical vertebra^ slightly con- 

 cave at the ends. Atlas, axis, and third cervical coossified. 



Teeth. Eight maxillary teeth of the left side, showing more or 

 less signs of wear, are in place. They are all of much the same size 

 and shape, but whether these constitute the complement of one side 

 of the maxillary bone is not known, although it is thought that if 

 there were any more the number did not greatly exceed eight. 



Of these teeth the one least worn and best preserved is here des- 

 cribed and figured (Plate XI, figure 2). 



The crown of this particular tooth is enamelled through- 

 out, is but slightly deeper than broad, and has a strong, tumid cingu- 

 lum constituting its base. This cingulum is less protrudent, and at a 

 lower level on the inner side than externally, giving the base of the 

 crown a decided obliquity of outline when viewed from the front or 

 back. The portion of the crown below the cingulum, in the form of a 

 short blade, has nearly the full breadth of the cingular part, and 

 descends to a point with denticulated border, but is thin interno- 

 externally in comparison with the thick base. The greater tumidity 

 of the cingulum externally, and the fact that the blade does not 

 descend fully in line with the axis of the root but is retired somewhat 

 inward, gives a decided concavity to the external face of the crown 

 which is absent internally, the inner face of the blade being flat or 

 inclined to convexity below the shelf of the cingulum. 



There are five denticulations on the crown's anterior border, 

 and apparently three on the posterior one which is injured. The 

 additional one, forming the point of the tooth, is larger than the lateral 

 ones. Both externally and internally, the crown is marked longitudin- 

 ally by fine anastomosing, discontinuous rug^e which are somewhat 

 accentuated on the lower curve of the cingulum. The outline of the 

 denticulated anterior border of the crown has a more decided curve 

 than that of the posterior one, viewing the crown from within or with- 

 out. The root of the tooth is long, smooth-surfaced, and subcylin- 

 drical with a broadly oval cross-section of which the fore and aft 

 diameter is the greatest. A pulp cavity is present and occupies about 

 one-third of the diameter of the root. 



The tooth is worn on the inner side in a small surface above the 

 apex toward the front and on the prominence of the cingulum near 

 the front, proving that the upper teeth bit outside the lower ones, as 

 would be expected. 



Sec IV, Sig. 4 



