EXPLANATION OF PLATES 



[ All the figures are by the author, and are of natural size, except where other- 

 wise stated.] 



Frontispiece. — Mounted skeletons of Varanosaurus hrevirostris Williston, 

 and Casea hroilii Williston, a little less than one-sixth natural size. Walker 

 Museum, University of Chicago. Skeletons collected, prepared, and mounted 

 by Paul C. Miller. 



Plate I. — Varanosaurus hrevirostris Williston. Fig. i, dorsal ribs, a, b, d, 

 left, from behind, c, right, dd, same as d, from in front; Fig. 2, odontoid of 

 atlas, axis, and third to fifteenth vertebrae, from the side. 



Plate II. — Varanosaurus hrevirostris Williston. Fig. 2, fourth to fif- 

 teenth (thirteenth to twenty-fourth presacral) vertebrae from below; Fig. 2, 

 sixteenth to twenty-seventh (first to twelfth presacral) vertebrae, from the side; 

 Fig. 3, the same, from below. 



Plate III. — Varanosaurus hrevirostris Williston. Sacral and caudal 

 vertebrae in continuous series to the forty-seventh, as found in articulation; 

 with anterior and distal chevrons. 



Plate IV. — Varanosaurus hrevirostris Williston. Fig. i, interclavicle 

 and clavicles in articulation; Fig. 2, interclavicle from left side; Fig. 3, left 

 clavicle, from below; Fig. 4, right clavicle, from in front; Fig. s, right scapula- 

 coracoid, from behind; Fig. 6, right proximal tarsals, a, tibiale; 6, fibulare; 

 Fig. 7, the same, ventral side; Fig. 8, sacrum, from below. 



Plate V. — Varanosaurus hrevirostris Williston. Right scapula. Fig. i, 

 from outer side; Fig. 2, from inner side; Fig. 3, from above; Fig. 4, from below. 



Plate VI. — Varanosaurus hrevirostris Williston. Fig. i, right humerus, 

 ventral side; Fig. 2, the same, ulnar side; Fig. 3, the same, dorsal side; Fig. 4, 

 the same, radial side; Fig. 5, the same, distal end; Fig. 6, the same, proximal 

 end; Fig. 7, sacrum, from in front; Fig. 8, first presacral vertebra, from in 

 front; Fig. 9, twelfth presacral (fifteenth postcranial) vertebra, from behind. 



Plate VII. — Varanosaurus hrevirostris Williston. Fig. i, left radius 

 and ulna, dorsal side; Fig. 2, the same, ventral side; Fig. 3, left ulna, radial 

 side; Fig. 4, left radius, ulnar side; Fig. 5, ulnare, ventral side; Fig. 6, left 

 ulna of another individual, dorsal side; Fig. 7, a, odontoid of undetermined 

 pelycosaurian, from in front, h, from the side, c, from behind; Fig. 8, carpus of 

 Dimetrodon incisivus Cope, ventral side, two-thirds natural size {R, radiale; 

 U, ulnare; C i, 2, centralia; 1-5, carpalia). 



Plate VIII. — Varanosaurus hrevirostris Williston. Left forearm and 

 hand, dorsal side. 



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