1450 CLASS MAMMALIA. 



tition, by the reduced number of incisors, and the absence of the 

 inflection of the angle of the mandible, and of palatal vacuities. 

 By others they have been regarded as closely allied to certain fami- 

 lies of the Insectivora, and, together with the latter, are classed as a 

 section of a large and ill-defined order termed the Bunotheria; 

 while a third writer ranks them as an order of equal value with the 

 existing Insectivora and Camivora. Their relationship appears, 

 however, on the whole, to be decidedly nearest to the true Carni- 

 vora, and they are accordingly here classed as a division of that 

 order. They undoubtedly, however, exhibit affinities to the Insect- 

 ivora, from which they are distinguished by the Carnivorous type of 

 their incisors and canines ; while the remarkable resemblance ex- 

 isting between their cheek-teeth and those of the Polyprotodont 

 Marsupials is probably indicative of a distinct genetic relationship 

 with that group. Mention has already been made of their resem- 

 blances to the Condylarthrous Ungulates. 



The following are the chief characters of this suborder : The 

 brain is of relatively small size ; the fourth upper premolar and the 

 first lower true molar are not differentiated as an opposed pair of 

 carnassials, but resemble more or less closely the tooth immediately 

 behind or in front of them, which is either conical or of a more or 

 less secant type ; and the upper true molars are either subtriangular 

 or simply secant. The tibial face of the astragalus is, moreover, 

 generally devoid of a groove ; the scaphoid and lunar are usually 

 separate ; the femur has a third trochanter ; and the feet were plan- 

 tigrade. In all cases where there is the full number of incisors, the 

 second pair in the lower jaw is thrust up above the other two, as in 

 so many of the Carnivora Vera. The structure of the cranium ap- 

 proximates to that of Amphicyon. 



Family Hy^enodontid^e. — This family includes the most special- 

 ised forms. The dentition (fig. 1336) is of a markedly sectorial 

 type, the inner tubercle of the hinder upper cheek-teeth being very 

 small ; and there is no inner cusp to the lower true molars. In 

 the type genus the scaphoid and lunar of the carpus were united. 



Hyoenodon has the dental formula I. -, C. -, Pm. -, M. - ; the 



3 1 4 3 



inner tubercle of the two upper true molars is almost wanting, and 

 the third lower true molar differs from the two. teeth in front (fig.. 

 1336), and somewhat resembles the carnassial of Felts. This genus 

 includes species varying in size from a Leopard {If. horridus) to a 

 small Fox {If. vulpinus), and is widely (distributed both in time and 

 space. Thus it is found in Europe, and also in North America, 

 where it ranges from the Upper Eocene to the Lower Miocene; 

 while in India it survived into the Pliocene. One species has been 

 found in the Upper Eocene of Hampshire. The species from the 



