122 The Ottawa Naturalist [January 



of the dental magazine appear to have their margins smooth or with 

 only a slight indication of papillae near the top. In the broadest part 

 of the dental grinding surfaces there are generally two functional 

 teeth in a transverse direction. The estimated number of teeth in the 

 dentary in each vertical series near the midlength of the dental 

 magazine is about three. There are about thirty-five vertical rows of 

 teeth in the maxilla and thirty-three in the dentary. The above small 

 Belly River form with long, narrow teeth may prove to be ancestral 

 to Cheneosaurus. 



The predentary was missing in the type skull but has been 

 restored, as figured, principally from the smaller skull, in which this 

 bone was preserved. As in the premaxillae the front margin is coarsely 

 notched, indicating the probable presence in life of a firmly attached, 

 strong, horny covering to the beak-like termination of the jaws. 



About thirteen sclerotic plates are wholly or partially preserved 

 in the upper part of the orbital opening. The ring in which these 

 plates occurred in life is clearly indicated but its symmetry is destroyed 

 and the full number of plates may not be represented. 



With the skull are figured the odontoid process, the axis, and the 

 third cervical vertebra which were found in place. The remaining 

 parts of the atlas were missing. 



Measurements of the type skull of Cheneosaurus 



tolmanensis. 



Mm. 



Length of cranium from anterior end of premaxillae to occipital 



condyle 445 



Length of cranium from anterior end of premaxillae to posterior 



border of exoccipital process 477 



Height of skull, as mounted, from lower surface of dentary ver- 

 tically upward to highest point of upper surface 308 



Distance from lowermost portion of jugal to highest point of 



superior surface of skull 276 



Distance from grinding surface of maxillary teeth to highest 



point of skull 1 22 



Anterior premaxillary breadth from midline of skull to outer 



angulation (half breadth of snout) 97 



Length of quadrate (slightly restored at lower end) 190 



Extreme length of mandible (predentary restored, articular 



restored) 473 



Length of dentary 358 



Depth of dentary, at about midlength of mandible, from outer 



alveolar border to lower edge 64 



Maximum breadth of predentary (restored) 151 



Maximum height of orbit 99 



