GEOLOGICAL SUEVEY OF THE TEERITORIES. 557 



Among Carnivora^ the feet are like both dogs and bears. The very- 

 prominent postglenoid ridge, and the narrow tympanic chamber* are 

 decided points of resemblance to the bears, but the cavum tympani is 

 even less expanded than in those animals. The characters of dentition 

 are more like those of the Hywnodontidoe and Mesonyx than any other 

 group, and even the remarkable incisor-like inferior canines are approxi- 

 mated by the anteriorly directed canines of Hycenodon leptorhynchus, 

 Laiz. et Par. 



As a summary, it may then be concluded that the genus Synoplothe- 

 rium is a Carnivore, presenting a number of points of resemblance to 

 the bears, and to the extinct Hycvnodons ; but that its distinct scaphoid 

 and lunar bones, and iiat claws ally it to other forms of Mammalia, show- 

 ing it to be a more generalized type of the order than either of the 

 above. The peculiar approach of the lower canines is a special modifi- 

 cation for peculiar habits, which I suspect to have been the devouring 

 of the turtles which so abounded on land and in the waters of the same 

 period. The slender symj)hysis could most readily^ be introduced into 

 the shell, while the lateral pressure of the upper canines .with the lower, 

 would be well adapted for breaking the bony covering of those reptiles.} 

 It is not unlikely that this genus, Mesonyx, and possibly ^ycewoc^ow form 

 port of the lost series which terminated in the Seals of the present. 



Synoplotherium lanius. Cope. 



Proceed. Amer. PMlos. Soc, 1872, p. 483. 



The cranium of this species is rather less than that of the grizzly 

 bear, while the other bones do not indicate so large an animal. 



Measurements. 



M. 



Length glenoid cavity 0. 045 



Width glenoid cavity 025 



Diameter zygomatic fossa 058 



Width opisthotic inside for. stylohyoideum 014 



Diameter meatus auditorius estemus 012 



Diameter cavum tympani 009 



Length ramus mandibuli preserved 228 



Length of series of seven molar teeth 131 



Length of. last molar crown 0155 



Width of last molar crown 0080 



Length of penultimate crown 0215 



Width of penultimate crown 0100 



Length exposed part of inferior canine 024 



Length exposed part of superior canine 032 



Length exposed part of outer upper incisor . 023 



Diameter triturating-surface inferior canine ^ . 028 



Diameter triturating-surface do., transverse 0166 



Diameter superior canine, (antero-posterior) 024 



Diameter of the two inner incisors - 010 



Diameter of exterior incisor, (oblique) 010 



Diameter symphysis mandibuli 044 



Diameter nareal oriiice 040 



Depth nareal orifice 031 



Depth mandibular ramus atM. 6 049 



Thickness below of ramus atM. 6 - 014 



Length of a superior molar crown 020 



* See Professor Flower's Osteology of Mammalia on this point. 

 + See Proceed. Amer. Philos. Soc, 1872, p. 484. 



