300 0. P. Hay — Species of SaurocepJialus. 



curved, and is occupied by compressed sharp-edged teeth. Of 

 these there are present twenty-eight ; but if we restore the 

 bone, as we can safely do, I believe, by aid of Stewart's figures 



Fig. 1. 



of S. dentatus* we may conclude that there were originally 

 thirty-four teeth, possibly one or two less. The root of the 

 most anterior tooth has been exposed by the fracture, and its 

 fang is seen to be distinctly faceted ; so that it presents just 

 such an appearance as the tooth of S. lanciformis figured by 

 Leidy. f The roots of teeth situated more posteriorly whose 

 fangs have been exposed by a tool are similarly faceted. Cope 

 states;}; that S. lanciformis is to be distinguished from his S. 

 arapahovius, by the lack of facets on the roots of the teeth 

 of the latter. 



Leidy estimated that the maxilla in his hands had supported 

 only twenty-six or twenty-eight teeth, and he was probably 

 correct. That maxilla, a larger one than the one in my posses- 

 sion, seems to have been broken just behind the palatine con- 

 dyle. If now we take from Leidy's drawing the width of the 

 bone at this point and apply it to the alveolar border, we find 

 that it includes ten teeth ; the width of my own specimen 

 includes thirteen teeth. It is not impossible, however, that the 

 specimen figured by Leidy had been broken away some little 

 distance behind the condyle. At any rate, I do not believe 

 that the difference of a few teeth, other things being alike, 

 would justify us in regarding the specimens as belonging to 

 different species. 



As in the case of the original specimen there is a shallow 

 groove running along the mesial surface of the maxilla, about 

 5 mm from the alveolar border, and from this groove foramina, 

 one for each tooth, enter the bone. 



Depth of maxillary at palatine condyle 38 mm 



Distance from anterior end of palatine condyle 



to hinder end of maxillary 85 mm 



The right mandible is shown in fig. 2, five-eighths the natu- 

 ral size and showing the mesial surface. The alveolar border 

 is straight and supports thirty-four teeth, of which those occu- 

 pying the middle of the border are the largest. In general, 

 they are larger than the teeth of the upper jaw. The line 



* Kan. Univ. Quart, vii, p. 25, pi. i, figs. 3a, 4a. 



t Trans. Amer. Philos. Soc, xi, pi. vi, fig. 9. \ Cretaceous Vertebrata, p. 216. 



