1885.] DR. ST. G. MIVART ON THE ARCTOIDEA. 345 



the bulla can be seen, or if a probe is passed into the meatus, no 

 obstacle will prevent its touching the inner wall. Whatever the 

 diversity of development of the bulla, it always has its greatest pro- 

 minence near the middle of the inner border, and slopes away from 

 that point, not only externally, but also forwards and backwards. 



" (2) The inferior lip of the external auditory meatus is always 

 considerably prolonged. 



"(3) Tlie paroccipital process is more or less triangular, and 

 directed backwards, outwards, and downwards, standing quite aloof 

 from the bulla. This relation depends chiefly on the want of deve- 

 lopment of the posterior portion of the bulla, and is absent or obscure 

 in Mustela alone. 



"('I) The mastoid process is widely separated from the paroccipital, 

 and generally very prominent. 



"(5) The carotid foramen is always large, and placed usually near 

 the middle, but sometimes more posteriorly, on the inner margin of 

 the bulla. It is generally very conspicuous, but sometimes partially 

 concealed by the projecting lip of the basioccipital. 



"(6) The condyloid foramen is distinct and exposed, and although 

 sometimes partially overlapped posteriorly by a ridge of bone passing 

 from the paroccipital to the condyle, it is never sunk into a common 

 opening with the foramen lacerum posticum. 



" (7) The glenoid foramen is always present, and generally very 

 conspicuous. In Enhydris it is least so. 



"(8) The alisphenoid canal is present in the true Bears and Ailurus, 

 absent in all the others. Hence it cannot be used to characterize 

 the entire group, though useful in aiding its subdivision. 



" The group thus defined is, I think, too extensive, and presents 

 too great variation among its members, in dentition and external 

 characters, to constitute a family, as proposed by Mr. Turner. I 

 would rather regard it as a primary section of the fissipedal Carni- 

 vora, to which the name of Arctoidea might be given. 



"I perfectly agree with Mr. Turner that it is further divisible 

 into four chief sections, or families as I should call them — the 

 Vrsidce, Ailuridce, Procyonida, and the Mustelidce, 



" Of the Arctoidea, the true Bears are the most specialized or 

 aberrant ; they form a very compact group, distinguished by their 

 very characteristic dentition, and their completely plantigrade mode 

 of progression. They have a very wide geographical range. On 

 the other hand the Proci/onidee, though few in numbers and re- 

 stricted to the warmer and temperate parts of the American conti- 

 nent, are structurally less closely connected, at least if the singular 

 CercoJeptes is truly a member of this group. Except for the in- 

 creased number of the molar teeth, which is the only definite cha- 

 racter by which they can be separated from the Mustelidm, I see 

 no reason for considering the ProcyonidiB more nearly allied to the 

 Vrsidce than are the other families of the group, or for speaking of 

 them as specially ' subursine.' 



"Ailurus (an unfortunate name for an animal so essentially Arctoid) 

 appears to me to be an isolated form. Its dentition, though re- 



