24 
fishes of the Tertiary era, from the Green River, Wyoming beds, 
and miscellaneous specimens of exceptional size and beauty. 
Case 1 A, Hall 35.— Fossils of the Laurentian period. The 
existence of life at this period has not been definitely proved by 
any remains found as yet. A supposed fossil, Eozdon Canadense, 
is illustrated by several specimens. 
The specimens are made up of alternate layers of calcite and 
serpentine, which are thought by some to represent the shell and 
body cavity of an ancient, huge Rhizopod. Others regard the 
masses as of wholly inorganic origin. 
The remainder of Case 1 and Cases 2 A-F.— Fossils 
of the Silurian age or age of Invertebrates. The life of this age is 
almost wholly marine and made up chiefly of corals, crinoids, 
brachiopods and mollusks. It is illustrated in the collection ac- 
cording to periods as follows: 
Case 1, A and B.— Cambrian and early Silurian fossils. 
Oldha??iia—^xoh 2 i\AY a plant of the order of marine algae; 
Brachiospongia—2i representative of the class of sponges; Monti- 
culipora — of corals. 
Diplograptus, Teiragraptus—Hydxoxdis known as graptolites, 
abundant fossils of this era. The name is derived from the Greek 
word meaning “to write,” and refers to the plume-like nature of 
their remains. Scolitkus—s\r^^ostd to represent the borings and 
tracks of worms. 
Tentaculites—mmvXt mollusks of the class of Pteropods. 
Conularia — perhaps also Pteropods. 
ParadoxideSy AsapAus, Olenellus, Agnostus—TxUobites, the 
most common and characteristic fossils of early Silurian times. 
They were crustaceans, allied to the horse-shoe or king crabs of 
the present day. Two models illustrate the various parts of their 
structure, and tracks of a trilobite, genus Climatichnites, are shown 
on a large slab of sandstone from Wisconsin. The number of 
important animal types having existence in even the earliest geo- 
logical periods is worthy of note. 
Between Cases i and 2, a cast of an Orthoceras, nine feet in 
length. This shows the size which these Cephalopods, repre- 
sented at the present time by the nautilus, attained in early times. 
They were a striking feature of the Palaeozoic era. 
Case 2 A. — Trenton and Cincinnati epochs. Receptaculites^ 
Selenoides — probably calcareous sponges. Favistella—Cox^Xs be- 
