41 



below Uie posilum (if llic last nioliir lootli is rafhcr more eonspiciKiusly lulicr- 

 ous and roughened for muscular attachment, and the concavity back of this 

 is more posterior and deeper than in the first-described specimen. 



Comparative measurements of the lower-jaw specimens, including the one 

 first described, are as follows : 



Space occupied by tlie entire molar series 



Space occupied by the molars and last two premolars . 



Space occupied by the true molars 



Distance from last molar to back of jaw 



Width of ramus back of condyle 



Depth of ramus at middle of last molar : . . 



Depth of ramus below last premolar 



Thickness of base below second molar 



Anteroposterior diameter of last molar 



No. 1. 



Lines. 



C4 

 .40 

 49 

 44 

 31 

 23 

 13 

 19 



No. 2. 



Lines. 



05 

 48 

 48 

 41 

 3U 

 23 

 11 

 20 



No. 3. 



Lines. 



00 

 4.5 



33 

 20 



12 

 19 



No. 4. 



Lines. 

 78 



02 

 45 



33 

 29 

 13 

 19 



A small fragment of the chin of a lower jaw, referable to Paleeo.syops, 

 retains part of the alveolus of a large canine, and portions of the fangs of 

 three incisors of the same side, thus indicating the number of the latter teeth 

 in the animal. The canine alveolus has been about an inch in diameter. In 

 the ramus of the jaw above described, retaining the fang of a canine, this 

 tooth has been nearly in proportionate size to that of the alveolus just men- 

 tioned. 



Small fragments from three different skulls, attributable to Palceosyops, 

 consisting of portions of two sagittal crests and the supra-occipital, indicate 

 capacious temporal fossa?, separated by a short, thick crest and a broad 

 occiput. 



The fragments of sagittal crests arc from the fore part, retaining the suture 

 and notch for the summit of the frontal. The upper surface of the crest is a 

 flat triangle, slightly depressed at the middle, with the notch for the frontal 

 in its base. In the latter position it is li inches wide; and a couple of inches 

 back of this position the crest is !| of an inch thick. 



The occipii'il fragment on each side in front presents a widc!, sloping sur- 

 face, which contributes to the temporal fos.sa. The posterior surface in 

 general ap])earance resemljles that in the rhinoceros. Tiie upjier ])ortion 

 forms a broad, even concavity, undivided by any trace of a vertical ridge, and 

 6 G 



