35 
with scales. Plants are represented by leaves of the Walchia, a 
Lycopod. The fossils of the Carboniferous Age are especially 
numerous in the State of Illinois, and a good description of them 
can be obtained from the report of the Geological Survey of 
Illinois, Volume II, which may be found in the Library. 
South and West Walls of Hall 36.— Large slabs and 
casts showing tracks of reptiles of the Triassic period. Little is 
known about these animals, except so much as can be learned from 
their foot-prints. The Brontozoum was a three-toed animal, proba- 
bly at least 14 feet in height, and had a stride of over 3 feet. 
Cheirotherium{SoM\h Wall, Hall 59) was so named from the resem- 
blance of the foot-print to the human hand. It was a four- or five- 
toed reptile, probably of the order of the Labyrinthodonts. A cast 
showing the shape of the skull of the latter animal may be seen at 
the right. 
Cases 5, 6, 7, part of 8, and Walls of Hall 59. — 
Fossils of Mesozoic Time, the age of reptiles. This age is charac- 
terized by the number and size of its reptiles, especially Amphi- 
bians. Here, too, are introduced the first mammals, birds, and 
fishes of the modern type, and among plants the angiosperms- 
Cases 5 A and B.— Triassic fossils. Many of the types of 
the Carboniferous age continue to be prominent. Eqicisetuin^ be- 
longing to the family of Equisetae, or “ Horsetails ” of the present 
day, and Pterophylliim, of the order of Cycads, were most promi- 
nent among the land plants, and are illustrated by many speci- 
mens. Among the Lamellibranchs, the modern genus of Modiola 
is introduced. Ceratites represents the Orthoceras of early times, 
from which it will be seen to differ in being coiled, and in having 
a more complex suture. 
Cases 5C, I), E, F, G, 6, 7, 8 A, B, C, D, and Walls 
of Hall 59. — Jurassic fossils. 
This is the period when the class of reptiles reached its great- 
est development. Other interesting fossils are found, however. 
Cases 5D, E, F, G. — Among plants, Cycads are illustrated 
by several specimens of Cycadoidea, Conifers and Ferns are also 
shown. Among Invertebrates the beautiful Crinoid Pentacrinus ^ 
three specimens on the south wall, is especially notable. Other Echin- 
oderms are Cidaris, Hemicidaris, Pygaster and Clypeaster, the two 
latter being allied to Clypeits or “sand dollar” of the present d^-y. 
