Eaton — John Day Felidcc in Marsh Collection. ±*27 



Merriam, lately of the University of California, has very 

 kindly supplied certain measurements of his types of 

 Pogonodon davisi and Nimravus {Archodurus) debilis 

 major in addition to those given in his original 

 description of these two types. The illustrations accom- 

 panying this article are by Mr. R. Weber, and have a 

 value of their own quite apart from the text. 



Where the number of species to be compared is large, 

 interpretation of the absolute measurements is facilitated 

 by a further table expressing relative cranial pro- 

 portions. The system of indices, so extensively used 

 by anthropologists, eliminates the factor of mere size and 

 is admirably adapted to this requirement. Accordingly 

 the basal length, measured from basion to prosthion, 

 which is probably the most rational single element of 

 size, has been chosen as a convenient basis for the com- 

 parison of the major cranial proportions. From several 

 of the cranial measurements in Table A, indices have 

 been derived by the simple process of dividing these 

 measurements, as taken on each skull, by the basal length 

 of that skull, and multiplying the quotient by 100. In 

 the case of minor cranial proportions and dental pro- 

 portions, other dimensions than the basal length are more 

 suitable as the bases of comparison ; but as in every case 

 the definitions of the indices, arranged in Table B, refer 

 to the serial numbers of the absolute measurements, 

 recorded in Table A, no confusion regarding the identity 

 of the indices in Table B need arise. 



The measurements recorded in Table A call for little 

 explanation. The axial length from the prosthion to the 

 posterior surfaces of the occipital condyles has been 

 retained principally because of its long use by previous 

 authors as a convenient over-all dimension ; but the basal 

 length from basion to prosthion, which can be readily 

 taken in some skulls where Cope's axial length is impracti- 

 cable, has been preferred as a basis for the comparison of 

 size and proportion. There has been little uniformity in 

 the past regarding the measurement of palatal length. 

 The margin of the palatine bones bounding the posterior 

 nares is seldom perfectly preserved, and even when com- 

 plete it seems to be subject to some individual variation of 

 form due to the development of a posteriorly directed 

 mid-line process homologous with the posterior nasal 



