i>(^ FIELD MUSEUM OF NATURAL HISTORY 
A skull of the primitive bear Amphicyon, skulls and skeletons 
of smaller carnivores, and skulls, feet and legs of three-toed 
horses. Also a mounted skeleton and series of skulls of Pro- 
}ncrycoclucnis, a successor to Orcodon of the last epoch; skulls 
of Mcrycochccrus, Mcrychyiis and other members of the Oreo- 
dont family, and skulls of Oxydactylus and Procamehis, members 
of the camel family. A complete skeleton of Oxydactylus is also 
shown. 
Another fossil from beds of this age shown is Dcemonelix, or 
Devihs Corkscrew, a curious spiral form found in great abun- 
dance in the sandstone strata of western Nebraska. Its exact 
nature is problematical. Some think that it represents the remains 
of aquatic plants. According to another theory natural casts of 
ancient gopher burrows form the fossil. The series shown is 
thoroughly representative, and includes specimens of supposed 
stages of development of the form. (Hall 60.) 
Other Tertiary forms represented include: 
Restoration of Colossochelys atlas, a huge turtle which lived 
in India during the Tertiary period. (Hall 60.) 
A restoration showing the jaws of Carcharodon, and within 
these, for comparison, the jaws of a modern shark. The Car- 
cJiarodon was probably 50 to 70 feet in length. (Hall 60.) 
Quaternary Vertebrate fossils of the Quaternary 
period are represented in the collection by remains of the masto- 
don, mammoth, bison, rhinoceros, Irish deer. New Zealand birds, 
cave bear, and cave man, as well as by a large series of casts 
and restorations. The largest of the specimens is the skeleton 
of the mastodon from southern Michigan. This was an ele- 
phant-like mammal, differing from the elephant in having a 
more elongated body, shorter and stronger limbs, flatter cra- 
nium and less complex molars. The grinding surfaces of the 
molars were more or less tubercular, in contrast to the ridges 
which characterize the teeth of the elephant. Hence comes the 
name, mastodon, nipple tooth. The animal probably had no 
hairy covering to enable it to endure a rigorous climate as did 
the mammoth. In addition to the skeleton from Michigan a 
skull and tusks from Yorkville, Illinois, are shown. (Hall 59.) 
The skeleton of the Irish deer is from Limerick, Ireland. 
It is that of a large Post-Pliocene deer, the bones of which are 
occasionally found in marl beneath peat beds in Ireland and 
