NO. 2 



EXTINCT HORSE FROM ALASKA — HAY 



numbered 4, the vertex length ; that numbered 6, the facial length ; 

 that numbered 7, the cranial length ; that with the numeral 12, the 

 frontal width. From these measurements we may obtain certain 

 indices, viz., the cephalic index (measurement 12 x 100-r- measure- 

 ment 2) ; the facio-cephalic index (measurement 6x 100^- measure- 

 ment 2) ; and the cranio-cephalic index (measurement 7 X 100-f- meas- 

 urement 2). These operations performed give us the following 

 results. For comparison, there are included the same indices deter- 

 mined from the skull of a large Percheron gelding, No. 174960, 

 U. S. N. M. ; from the skull of an Arabian horse, No. 172454, U. S. 

 N. M. ; from four skulls of Grevy's zebra (Equus grevyi) ; from 

 four skulls of Grant's zebra (Equus burchelli granti) ; and from three 

 skulls of Equus przevalskyi. 



These details are added for the purpose of contributing to the 

 determination of the value of the various indices which have been 

 employed in determining the races and species of horses. All the 

 skulls employed in these estimates belong to the U. S. National 

 Museum, except those of Equus przevalskyi. These are in the Amer- 

 ican Museum of Natural History, where the author has been kindly 

 permitted to study them. The zebras were collected by the Smith- 

 sonian African Expedition of 1909, most of them by Mr. Edmund 

 Heller. 



Indices 



Cephalic index 



Facio-cephalic index 



Cranio-cephalic index 



Palato-cranial angle, in degrees 



E. burchelli granti 



161930 161932 162962 162955 



40.9 

 74.2 

 36 

 6-5 



40.2 

 75-6 

 36.4 



41 



76.3 

 36.8 

 18. s 



40 

 74-3 

 39-1 

 17 



E. przevalskyi 



136 32686 



43-1 43 

 76.9 77 



36.2 i 36 

 19 15-5 



43-2 

 76.2 

 33-7 



I/-5 



As regards the cephalic index, it will be observed that, especially 

 among the skulls of Grevy's zebra, there is a good deal of variation. 

 It has been regarded as an animal possessing a very long, narrow 

 skull ; while Grant's zebra, to the eye, seems to have a rather broad 



