No. 392.] REVIEWS OF RECENT LITERATURE. 665 
independent of the customary food of the species. When placed 
in the dark, the green organisms disappear and the death of the 
Amceba by hunger ensues. Colonies thrive in minute drops of 
water which would quickly foul were not the Zodchlorellz present to 
renew the supply of oxygen. Ci 
ZOOLOGY. 
The Fossil Bisons of North America. — Mr. Frederic A. Lucas, 
Curator of the Division of Comparative Anatomy in the U. S. National 
Museum, has published a most valuable contribution to our knowledge 
of the Fossil Bisons of North America. His paper,’ consisting of less 
than twenty pages of text, is illustrated by twenty half-tone plates, 
mostly of skulls and horn cores, reproduced from photographs, and 
representing nearly all of the authentic material of this character 
relating to the subject. Mr. Lucas has evidently given much time 
and great care to the preparation of this excellent paper, and has 
placed the subject, so far as is possible from the scanty material 
at present extant, on a sound basis. That such a review was much 
needed is evident, in view of his conclusions. 
Seven species are recognized, the distinctive characters of which 
are based mainly on their horn cores, which he has found afford very 
good specific characters. The skulls, where available, are found to 
substantiate the differences shown by the horn cores. ‘The teeth of 
the various species so closely resemble those of the existing Bison 
that no attempt has been made to name or identify individual teeth. 
The localities from which Bison remains have been reported indi- 
cate that the group formerly occurred from Alaska southward to 
California, Arizona, and Florida; other localities are Idaho, Nebraska, 
Kansas, Texas, South Carolina, and Kentucky. They range in time 
from the Pleistocene to the present, and in all probability several of 
the species were contemporaneous. The seven species recognized by 
Mr. Lucas, with the localities at which their remains have been found, 
are as follows : 
(1) Bison bison(Linn.). Subfossil and recent. Remains in a semi- 
fossil condition have been found at Big Bone Lick, Kentucky ; Mill- 
wood, Kansas ; loess of the Missouri in the Winnebago Reservation. 
1 The Fossil Bisons of North America, Proc. U. S. National Museum, vol. xxi, 
pp- 755-771, Pls. LXV-LXXXIYV, with several text-figures. 
