428 Eaton — John Bay FelidcE in Marsh Collection. 



spine of the human skull. It has seemed desirable 

 therefore to discard the mid-line palatine length, and to 

 substitute for it a palatal length measured from the 

 prosthion to a line tangent to the posterior surfaces of 

 the maxillary parapets. This is precisely the same as 

 the external palatal length of human craniometry. 

 Since the index of palatal length, computed from this 

 dimension and the basal length, is remarkably constant 

 in all the species of Nimravus, Binictis, and Pogonodon 

 examined during the preparation of these tables, the 

 palatal length furnishes an excellent basis for computing 

 indices of palatal breadth. 



Pogonodon Cope. 



This genus was founded by Cope 1 on the characters 

 of a skull that he had originally described as Hoplo- 

 phoneus platycopis. 2 In a later article 3 he stated that 

 "This genus [Pogonodon'] represents a station on the line 

 connecting Binictis with the higher sabre-tooths, being 

 intermediate between the former genus and Hoplo- 

 phoneus," and provisionally referred to the same genus 

 incomplete material which he had made the type (partim) 

 of Machcerodus brachyops. 4 " Pogonodon platycopis and 

 P. brachyops were transferred by Adams 5 to Binictis, 

 the reason for this change being that "The genus Pogono- 

 don as proposed by Cope does not differ from Binictis 

 as regards tooth structure, and the absence of the second 

 inferior molar, which in Binictis is much reduced, is not 

 sufficient grounds for retaining it as a distinct genus, 

 since in several specimens of Binictis it is variable in 

 size and in one is absent from one side." Matthew 6 

 referred Pogonodon platycopis to Cope's genus Nimra- 

 vus, regarding Pogonodon as a distinct sub-genus ; and 

 to the same genus he referred P. brachyops also, stating 

 his opinion that the latter species was "like N[imravus] 

 gomphodus and doubtfully separable from it except by 

 absence of the infracarnassial exostosis." In the same 



1 E. D. Cope, Am. Nat., 14, 143, 1880. 



2 E. D. Cope, Am. Nat., 13, 798a, 1879. 



3 E. D. Cope, Am. Nat., 14, 847, 1880. 



4 E. D. Cope, Proc. Am. Phil. Soc, 18, 72, 1878. 

 5 C. I. Adams, This Journal (4), 1, 433, 1896. 



6 W. D. Matthew, Bull. Am. Mus. Nat. Hist., vol. 28, 310, 1910. 



