448 Eaton — John Day Felidce in Marsh Collection. 



Genus Nimravus. ' 



Four of the crania in the Marsh Collection, whose 

 measurements and indices have been included in the 

 tables, require but brief mention. Those listed under 

 the numbers 10044, 10045, and 10517 have been referred 

 to Nimravus debilis because on the whole, although they 

 differ mutually in minor characters, they resemble A T . 

 debilis and N. debilis major rather than N. gomphodus. 

 It is true that these three crania have almost exactly the 



Fig. 7. 



Fig. 7.— Nimravus debilis (Cope). Cat. No. 10517, Y. P. M. X %■ 



same basal length as the type of the latter species, viz., 

 198 mm. ; but the argument, founded on size alone, fails, 

 since within the species N. debilis, the basal length has 

 a range variation from 176 mm. to 211.4 mm., as shown 

 in Table A. 



Three views of the cranium designated as No. 10517 

 are given in figures 7, 8, and 9, and two views of the 

 cranium No. 10045 appear in figures 10 and 11. The 

 mandible of the latter is the better preserved of the two, 

 and is believed to show the form of masseteric fossa 

 regarded by Merriam as characteristic of N. debilis and 

 N. debilis major. The following is quoted from 

 Merriam 's painstaking discussion of Cope's Nimravus 

 gomphodus and N. (Archcelurus) debilis : "Practically 

 the only character which seems distinctive is found in 



