NO. 2021. 



SXflNCT BISONS OF NORTH AMERICA— HAY 



167 



Measurements of skulls. 



It ought to be stated here that the measurements of the specunen 

 of B. priscus which were recorded by Mr. Lydekker m the catalogue, 

 as cited, differ from the corresponding ones here given, not having 

 been taken m the same way, the length of the horn-core, 375 mm., 

 being taken evidently in a straight line. It is further to be noted 

 that in the present paper the distance between the bases of the 

 horn-cores is taken across the forehead where the rough bases ap- 

 proach each other most nearly. Some authors appear to take the 

 measurement between other pomts. 



The skuU from California which has been regarded as B. antiquus 

 has honi-cores of nearly the same length as those of the Earlham 

 specimen, but they are of greater diameter at the base. We may 

 therefore regard the California skuU as being that of a buU; the 

 other, that of a cow. Is it then possible that the English skull with 

 a narrower forehead, greater width at the orbits, and immensely 

 longer horns, besides other differences, belonged to a bull of the 

 same species? The writer does not thmk so. 



BISON OCCIDENTALIS Lucas. 



The type of this species is in the United States National Museum 

 and has the catalogue number 4157, It was discovered by Sir John 

 Richardson, at Fort Yukon, Alaska, where the Porcupine River 

 empties mto the Yukon. The specimen consists of the rear of the 

 skull bearing the two horn-cores. Of the left horn-core the distal 

 extremity is missing. Inasmuch as a number of other specimens 

 which are to be referred to the same species have come to light, it 

 seems best to consider them. Figures are here presented of the 

 type skull (pi, 9, figs, 3, 4). 



The most nearly complete skuU of this species known to the writer 

 is one in the American Museum of Natural History. Through the 

 liberality of the officers of the museum the writer has been furnished 

 with photographs of this skull, and from these the figures here shown 



