11 
There is now on exhibition valuable material from the Drexel, 
Edwards, Angus, Elliot, Grote and Robinson Collections ; and 
new material will be displayed as soon as the space can be pro- 
vided. The collections in the department are in frequent use for 
reference by specialists and students. 
Department of Mammalian Palaeontology. — The plan of 
the department is to form representative series from each of the 
twelve successive horizons of the West, in order to present a 
historical development of the evolution of the mammals in North 
America. Thus far five horizons have been visited : the Laramie, 
Puerco, Wahsatch, Wind River and White River. 
The first expedition went out in 189 1 and explored the Wahsatch 
and Wind River beds. The department sent a second expedition 
into the Rocky Mountain region in February, 1892, under Dr. 
J. L. Wortman, assisted by Mr. O. A. Peterson. They first 
explored the Puerco beds of northwestern New Mexico, and after 
two months traveled north to Wyoming into the older Laramie 
beds, and in July they established a camp in South Dakota. The 
party was seven months in the field, and added altogether over 
one thousand specimens to the new collection of fossil mammals. 
From New Mexico were procured three hundred specimens 
which represent some of the oldest forms on the Continent. This 
collection is of special value because these fossils have been 
represented hitherto only in one other collection. In the Creta- 
ceous four hundred minute teeth were collected with difficulty ; 
these are also very rare. 
Of much more recent age are the fossils, which include ances- 
tral forms of Tapirs, Horses, Rhinoceroses, of the Deer, Camels, 
of the older carnivorous animals such as the Cats, besides repre- 
sentatives of many large extinct families. Several of the larger 
skeletons are sufficiently well preserved to be mounted upon large 
panels of plaster resembling the sandstone in which they were 
found originally ; among these are three Rhinoceroses of different 
types, one of which is as large as the modern Rhinoceros of 
Sumatra, and is the finest specimen of the kind yet discovered. 
All this collection is being worked out of the stone as rapidly 
as possible, and it is proposed to exhibit it in one end of the new 
Geological Hall. 
