204 LLOYDS NATURAL HISTORY. 



first Family, and by others in the second. It may be observed 

 that the Mustelidce, together with the Ursidce (Bears), differ 

 from the Felidce and Virerridce, in the absence of a partition in 

 the auditory bulla of the skull, as well as in certain other struc- 

 tural features of the same region. In consequence of these 

 essential differences, the Felidce and Viverridce^ together with the 

 allied Families of the Hycctiidce and Proteleidce, have been bri- 

 gaded together in one primary group with the designation of 

 yEluroidea ; while the Mustelidce and Ursidce have been linked 

 as the Arctoidea. The intimate connection shown to exist by 

 fossil forms between the Civets and Weasels on the one hand, 

 and betwixt Dogs and Bears on the other, indicates, however, 

 that such associations are altogether erroneous, and that the 

 absence of the partition in the auditory bullae of the Weasels 

 and Bears is in all probability an acquired character which 

 has arisen independently in the two groups. 



Whether the two genera now under consideration should be 

 placed in the Viverridce or in the Mustelidce is a matter of but 

 comparatively little moment, seeing that when we come to 

 primitive annectant types classification, as adopted in the case 

 of recent animals, becomes a practical impossibility. Since, 

 however, in the second of the two genera there is, at least, a 

 trace of the partition in the auditory bulla, the writer considers 

 it preferable that they should be placed here. 



Paheoprionodon is characterised by usually having but a 

 single pair of upper molar teeth, although there are two pairs 

 in the lower jaw, and its dentition corresponds, therefore, 

 numerically with that of the Linsangs in the present Family, as 

 well as with the majority of Weasels. In the general characters 

 of the base of the skull, and especially in the presence of an 

 alisphenoid canal, the genus resembles the more typical Viier- 

 ridcc, although the position of the so-called condylar foramen 

 at the hinder part of the base of the skull, as well as the pres- 



