CHARACTERS OF ARCTOIDEA 



425 



swollen, and there is but little flattening towards the meatus : 

 the paroccipital processes, though slight, are in contact with the 

 bullae basally, though their free tips are turned away from them. 

 Finally, in Ictonyx the bullae are much swollen ; there is but little 

 flattening towards the meatus, and the paroccipital processes, them- 

 selves much swollen, are pressed closely against the bullae. The 

 Mustelidae, therefore, in this as in other characters, approach the 

 Aeluroids. 



There is no caecum, a feature which marks off the Arctoidea 

 from all Carnivora except the Viverrids Nandinia and Arctictis 

 (occasionally). The brain is characterised by the possession of 



Cur- 



FIG. 212. Section of the left auditory bulla and surrounding bones of a Bear (Ursus 

 ferox). am, External auditory meatus ; BO, basioccipital ; Car, carotid canal ; 

 e, Eust'achian canal ; g, glenoid canal ; Sq, squamosal ; T, tympanic ; t, tympanic 

 (From Flower, Proc. Zool. Soc. 1869.) 



ring. 



what Dr. Mivart has described as the " ursine lozenge," a tract 

 about the middle of the hemispheres, defined posteriorly by the 

 crucial sulcus, and formed by the emergence on to the surface of 

 the brain of the hippocampal gyrus. 



The Arctoidea are very widely distributed. But there are 

 some curious exceptions. Thus there are no representatives of 

 the group (as might be expected) in the Australian region ; they 

 are completely absent from Madagascar; while the true Bears 

 (family Ursidae) are totally absent from Ethiopian Africa, and 

 are only represented by a single species, Ursus ornatus, in the 

 Neotropical region. 



It is noteworthy that the Arctoidea never show spots or 



