oscoop] SCAPHOCEROS TYRRELLI 183 
recognition. Thus far, only one specimen of this genus, the original 
type, has been found. Specimens of S. cavifrons and S. tyrrelli, 
however, have been secured at various localities among which are the 
following: Fort Gibson, Indian Territory; Council Bluffs, Iowa; 
New Madrid, Mo.; St. Louis, Mo.; Benton Co., Mo.; Trumbull Co., 
Ohio; Brook Co., W. Va.; Pennsylvania; Anvik, Alaska,t and 
Bonanza Creek, near Dawson, Yukon Territory. In this large num- 
ber of specimens, if there were any females at all it is probable that 
there would be more than one. In order to give any semblance of 
certainty to the supposition that the differences between bombifrons 
and cavifrons are sexual, it is necessary to show that these differ- 
ences are relatively the same that obtain between the sexes-in living 
species. This cannot be done, therefore it seems safer to treat the 
two animals as distinct. A much more reasonable assumption would 
be that S. cavifrons represents the male and S. tyrrelli the female of 
one species. The present objection to this is the fact that both have 
not been found in the same region. 
In order to make clear all the points under discussion, photographs 
are reproduced herewith of skulls of Ovibos moschatus, Bootherium 
bombifrons, Scaphoceros cavifrons, and S. tyrrelli. 
*A horn core of S. tyrrelli collected by Dr. Arthur Hollick at this locality 
in 1903 is in the U. S. National Museum. 
