1873.] "Vi [Cope. 



and lunar bones, and flat 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 

 modification 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 symphysis could most readily be in- 

 troduced 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 Hycenodon form part of the lost series which terminated in 

 the Seals of the present. 



Synoplotherium lanius. Cope, 



Proceed. Amer. Philos. 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 " " 025 



Diameter zygomatic fossa 058 



Width opisthotic inside for. stylohyoideum 014 



Diameter meatus auditorius externus 012 



" cavum tympani 009 



Length ramus mandibuli preserved „ .228 



" of series of seven molar teeth 131 



" last molar, crown 0155 



Width " " 0080 



Length of penultimate " 0215 



Width " " 0100 



Length exposed part of inferior canine t ..... . .024 



" " superior u 032 



" " outer upper incisor 023 



Diameter triturating surface inferior canine 028 



" do., transverse 0160 



" superior canine (antero-posterior) 024 



" of the two inner incisors 010 



' ' of exterior incisor (oblique) 010 



' ' symphysis mandibuli , 044 



" nareal orifice 040 



Depth " " 031 



" mandibular ramus at M. 6 049 



Thickness below of do 014 



Length of a superior molar crown 020 



Diameter condyle of humerus 047 



" shaft " (compressed) 0410 



" condyles " 0415 



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



