312 Mr. R. I. Pocock on the 



noticeably shorter and less well developed than in Pr ion- 

 ail ur us. 



Genus Ictailurus^ Severtz. 



" Ailurin," Gervais, 18-55, p. 86 ; for planiceps, Vig. & Horsf.*. 

 Idnilurus, Severtzow, 18o8, p. .387 ; type planiceps. 

 Ailurof/ale, ritzinjrer, 1869, p. 249 ; ty()e planiceps. 

 /Elurina, Gill, 1871, p. 60; type planiceps.. 

 PlethcBlurus, Cope, 1882, p. 475 ; type planiceps. 



Only one species hitherto admitted. 



Distr. ]\Ialay Peninsula to Borneo. 



The skull in its elongated shape, the structure of the 

 hullse, exceedingly compressed nasals, and deep postorbital 

 constriction recalls in a measure that o£ Zibcthailarus, but 

 may be distinguished by several peculiarities both dental and 

 cranial f. (1) The posterior border of the complete post- 

 (u'bital bar is scarcely convex owing to the great width o£ 

 the base of the malar portion. (2) The nasal branch of the 

 premaxilla is slender and tolerably evenly attenuated. 

 (3) The mesopterygoid fossa is very narrow, about twice 

 as long as wide or even more. (4) The muzzle is broad and 

 the palate nearly parallel-sided, the distance l)etween the 

 two anterior premolars being about equal to the distance 

 ])etweeu the inner cusps of the upper carnassials, and the 

 suborbital edge of the palate has a conspicuous and narrow 

 notch. (5) The occipital area is narrow, with a shallow 

 lateral emargination, and the summit much more poiuted 

 than^u Zibethuilurus. 



In the mandible the coronoid is low, with a wide summit 

 set well in advance of the backwardly projecting condyle and 

 angular. The anterior end of each ramus, carrying the 

 canine and inci:*or teeth^is strongly elevated, and there is a 

 large postcanine gap when the jaws are closed. 



In the teeth the first upper premolar is unusually large 



* Altliouo-h Gervais was the first autlior to give nominal distinction 

 to this genus, the name he proposed is inaduiissible, as a comparison 

 between it and such terms as " Chacal '" and *' Renard " of the same work 

 will show. By Gray planiceps was associated wiih viierrina under his 

 genus Viverriceps. 



t Whether the resemblances between these two cats are due to close 

 affinity or are merely adaptive it seems to me to be impossible to say. If 

 the former, the two supply an interesting exception to the general rule in 

 the Felidaj that thesmaller speciesof a genus have skullsoia more juvenile 

 type tlian the larger, owing to the lesser development of constrictions 

 and ridges associated with powerful masticatory muscles. I. planiceps, 

 although considerably smaller than Z. viverrina, has, nevertheless, a skull 

 indicatmg relatively greater masticatory power. 



