DAKOTA AND NEBRASKA. 



351 



Estimated length of the skull from the occipital foramen to the fore part of 

 the incisive alveoli, ...... 



Length of cranium from summit of the inion to the fronto-nasal suture, 



Length of skull from lateral border of inion to maxillo-premaxillary suture 



Distance from inion laterally to ant-orbital margin, 



Height of inion, ..... 



Breadth of inion, ..... 



Breadth at zygomata, .... 



Breadth of cranium above roots of zygomatic processes, 



Breadth at narrowest portion of cranium. 



Breadth at post-orbital eminences, . 



Breadth at ant-orbital margins, 



Breadth at infra-orbital foramina, . 



Length of face from ant-orbital margin, estimated, . 



Breadth at alveolar border where greatest, being opposite the ante-penulti- 

 mate molars, ..... 



Breadth at canine alveoli, .... 



Length of palate, ..... 



Greatest width of do. posteriorly, . 



Length of the molar series, .... 



Length of the series of the back four molars, 



Lines. 



29 

 18J 

 29 

 18J 



8i 

 13 

 17J 

 lU 



7 



8 

 lOi 



7 

 14 



9 



15i 

 4J 



11 

 5J 



ICTOPS. 



IcTOPS Dakotensis. 



Accompanying the skull oi Lepttdis, described in the preceding chapter, in Dr. 

 Hayden's last collection from the Mauvaises Terres, there is a fragment of a skull, 

 which on first view I supposed to belong to the same animal, but which on more 

 attentive examination proved to be part of another animal. The specimen, some, 

 what mutilated and distorted, is represented in figure 30, plate XXVI. It retains 

 portions of the frontals, nasals, and maxillaries, and further contains the remains of 

 most of the molar teeth of both sides. 



The fragment nearly agrees in form and size with the corresponding portion of the 

 skull of Leptidis Haydeni. Upon the sides of the forehead there are prominences 

 appearing like the anterior terminations of the temporal ridges of the latter, leading 

 to the supposition that these also existed in this animal. The anterior tenuiuation 

 of the frontals and the form of the nasals likewise resemble the corresponding parts 

 in LepAidis. 



