SIWALIK AND NARBADA CARNIVORA. 
29—206 
Eycenarctos ), it may be remarked that while one of the megalocreodont forms 
( Eycenarctos d’ Espagne 1 ) is of upper miocene age, none of the meionocreodont forms 
are known before the older pliocene. This is the more remarkable since the relative 
degree of the development of the carnassial to the hinder cheek-teeth (megalocreo- 
dontism) is indicative in some other groups of the Carnivora of high specialization, 
and therefore, the same may be presumed to hold good with regard to the bears. 
The explanation of this apparent anomaly is probably to be found in the supposition 
that the meionocreodont and megalocreodont bears at present known to us are 
diverging branches from a common stock, and that the common ancestors of the 
two are yet unknown. The very wide distribution in space of TJrsus and Eycenarctos 2 
also points to the conclusion that the common ancestor must have existed at a com- 
paratively early stage of the tertiary period. The suppression of the first premolar 
in Eycenarctos , and the more essentially sectorial nature of the carnassial, all confirm 
the conclusion as to this group of the megalocreodont bears being the most specialized. 
With regard to the disappearance of all the megalocreodont forms of the group 
(excepting the abnormal form Mluropus where the carnassial, though of relatively 
large size, is not of a markedly sectorial type) at the present day, it is not impossible that 
the more carnivorous nature of many of these forms, which is almost certainly indicated 
by the size and form of the carnassial, may have brought them into closer competition 
with the larger feline carnivores, and that not being such fleet animals they had not 
such good chances of obtaining their prey, and thus died out ; while the meionocreo- 
dont forms, which, with the exception of the peculiarly situated polar bear, are not 
extensively carnivorous, have still remained, and hold their place among the modern 
felines, without entering into direct competition with them. 
Genus I. : TJRSUS, LinnA 
Including Danis , Euarctos, Eelarctos, Melursus, Myrmarctos, Prochilus, Thalarctos , 
Thallasarctos, Tremarctos. 
Dentition , etc . — According to the arrangement adopted by Professor Flower in 
the catalogue of the osteological specimens in the Museum of the Royal College of 
Surgeons, the living bears are divided into two genera ; — namely TJrsus, and Melursus ; 
the latter comprehending only the so-called sloth-bear, or aswail ( Melursus labiatus ) 
of India, and the former all the other species. One important point of distinction 
of the skull of the sloth-bear is the absence in the adult of the inner pair of upper 
incisors ; while another is the relatively small size of the cheek-teeth. If, however, 
the cheek-teeth of an allied form were found in the fossil state apart from the palate 
it is improbable that they could be generically distinguished from the teeth of other 
bears, and it accordingly seems best for palaeontological purposes to merge the genus 
Melursus with TJrsus. It may be observed that the proper specific name of the sloth- 
l Gervais, op. cit., pi. LXXXI., fig. 2. 
2 Vide infra. 
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