28 FIELD MUSEUM OF NATURAL HISTORY 
A representative series of Mollusc shells is shown. In both 
the univalves and bivalves a close resemblance to modern shells 
will be noticed. Most of the genera are identical with living 
forms. Such are Venus, Cardita, Area, Tellina, Meratrix, etc., 
of Pelecypods, and Turritella, Cerithium, Strombus, Fusus, 
Murex, etc., of Gastropods. 
Vertebrate fossils from the Eocene, or first stage of the Ter 
tiary period, are represented by a series of fishes from the Green 
river shales and a cast of the large horned mammal, Dinoceras 
mirabile. 
The fishes from the Green river shales include a great num- 
ber and variety of bony fishes, or Teleosts, of modern types. 
Such familiar forms as the perch, the herring, and the ray are 
included. (Hall 59.) 
Dinoceras was a five-toed animal similar in size and in gen- 
eral proportions to the modern rhinoceros. It was character- 
ized by the presence of three pairs of horns on the head, a strong 
tusk-like upper canine tooth, and an elephant-like foot. It differs 
from existing animals in the number and arrangement of the horns, 
the V-shaped molar teeth, and the elephant -like foot. (Hall 61 .) 
Mammals of the Oligocene stage, or second subdivision of the 
Tertiary period, are represented by a great number and variety of 
forms, most of them having been collected by special expeditions 
sent out by the Museum. (Hall 59.) These arc mostly modern 
types of mammals. Among those represented are the primitive 
cats, dogs, squirrels, rabbits, camels, tapirs, horses and rhi- 
noceroses. There are also shown a number of the older types of 
mammals which had their origin in the first Tertiary stage and 
have no modern representatives. Among these are the Hyoe- 
nodon, Oreodon, Elotherium, Anthracotherium, Titanotherium, 
Hyracodon, and Metamynodon. The collection includes a 
mounted skeleton of the sabre-tooth cat, Dinictis, a representa- 
tive series of skulls of the primitive dogs, Cynodictis and Daph- 
cenus, of the three-toed horse, Mesohippus, the cursorial rhi- 
noceros, Hyracodon, the more typical rhinoceros, Aceratherium, 
the large suilline, Elotherium and the great horned ungulate, 
T itanotherium. 
Mammals from the Miocene, or third stage of the Tertiary 
period are represented by collections from two localities, the 
Deep River beds of Montana, and the Loup Fork beds of Ne- 
braska and Wyoming. They include the following forms: 
