BIG BADLANDS OF SOUTH DAKOTA. 



471 



been of uniform dimensions throughout, with a hemispherical termi- 

 nation. Some interesting differences in proportions appear in the 

 following measurements given by Leidy,*'^ to which have been added 

 the appropriate figures for the species described herein: 



A. ingens, 

 type. 



A. wanlessi, 

 type. 



A. scotti, 

 type. 



Height of symphysis (4 inches) 



Breadth of jaw outside of canine alveoli 

 (3 % inches) 



Breadth between ends of mental protuber- 

 ances (4M inches) 



Depth of jaw below first premolar (2% 

 inches) 



loi.s mm. 



955 

 121 

 70 



125 mm. 

 100 



92. 5 



73 



173 mm. 

 iio.s 



157 + 

 81 



The posterior processes are long affairs with constricted neck 

 and trilobate head, projecting outward and forward, the slope in 

 the former direction being intensified by crushing. 



To facilitate rapid comparison, the principal measurements are 

 included in the table on page 114, appended to the description of 

 A. wanlessi. 



The drawing (Fig. i), which has been traced from a photograph 

 and corrected from the original specimen, differs in many important 

 respects from Von Iterson's plate in Professor Scott's memoir,^ 

 especially in the delineation of the cheek flanges, the sagittal crest, 

 the mental processes, and in the omission of teeth not present in the 

 original, all of which greatly alter the contour of the skull as hitherto 

 figured. As no 'drawings of the teeth have been published, the fol- 

 lowing notes are added to aid in making comparisons : 



Upper incisors and canines had dropped out previous to fossiliza- 

 tion. Pi is a small double-rooted tooth placed obliquely to the gen- 

 eral direction of the tooth row and ii mm. (left) to 18 mm. (right) 

 back of the canine. It is well back of the canine on the right side, 

 but has its anterior edge almost in line with the posterior border of 

 the canine alveolus on the opposite side. The crown measures 25 

 mm. in long diameter on the alveolar border. P2 is reoresented by 

 an empty alveolus 26 mm. back of pj. P3 is also lacking, and there 

 is only a short space between it and p2, with the measurement of 



*■ Loc. cit., p. 192. 

 5 Log. cit., PI. XVII. 



