6o8 CARNIVORA 



that it is on the whole advisable to regard them as representing 

 a distinct suborder of Carnivora. In the strong development of the 

 canines (Fig. 278) they are distinguished from the modern Insect- 

 ivora ; and they also differ from the latter and resemble the true 

 Carnivores in the form of the incisors, the second one in the lower 

 jaw (when three are present) being thrust up above the level of the 

 other two in the manner obtaining in most of the modern Carni- 

 vora. Some of the most generalised forms included in the present 

 group approximate so closely to the Condylarthrous Ungulates as 

 to indicate that both groups have probably had a common origin. 



The Creodonta as a whole are characterised by the small size 

 of the brain, the absence of a single differentiated carnassial tooth, 

 and the triangular form or secant character of their upper molars. 

 In the carpus the scaphoid and lunar were usually distinct ; the 

 femur has a third trochanter ; the upper or tibial surface of the 

 astragalus usually wants the groove found in modern Carnivores ; 

 and the feet were plantigrade. The curious resemblance of the 

 molars of many of these forms to those of the Marsupials may 

 indicate a genetic relationship between the two groups ; but, on the 

 other hand, the presence of a full set of milk-teeth and the absence 

 of palatal vacuities, or of an inflection of the angle of the mandible, 

 sharply distinguishes them from that order. Space permits of a 

 notice only of the more interesting forms. 



Hycenodontidce. — This family is taken to include some of the 

 more specialised types, such as the European and American 

 Hycenodon and Oxhycena and the European Pterodon. In Hycenodon 

 (Fig. 278) the dental formula is i § , c ±, p -f-, m % ; the fourth 

 premolar above and the first true molar below being formed upon 

 the " carnassial " plan, but the teeth behind these, instead of being 

 tuberculated as in all existing Carnivora, repeat the characters of 

 the carnassial, and also increase in size, especially in the lower jaw. 

 from before .backwards. The last lower molar differs from the 

 two preceding teeth, and is very like the carnassial of Fein. The 

 scaphoid and lunar of the carpus were fused together. Some species, 

 as H. leptorhynchus, were as large as a Wolf, while others did not 

 exceed a Fox in size. Pterodon is readily distinguished by having 



, by the larger size of the inner tubercles of the upper molars, 



:55 



and the similarity in the form of the three lower molars. In some 

 species there were only two upper incisors, and the first lower pre- 

 molar may be wanting. Oxhya im is a specialised form with i -~ 3 » 

 c ], p |, m |, and a very long mandibular symphysis. 



Proviverridce. — The European and American genus Proviverra 

 (Cynohycenodon or Stypolophus) may be regarded as representing a 

 second family. The dental formula in this genus is the typical i ^, 

 c \, p ±, m : .\, the upper molars have a large inner tubercle, while 

 the lower molars are differentiated into a blade and talon, the 





