28 
Case 1 * — Fossils of the Cambrian and early Silurian periods. 
Several genera of Trilobites: Faradoxides, Asaphus, 0lenelluSy2ind 
Agnostus. This crustacean is related to the horse-shoe or king 
crabs of the present day, and is an abundant fossil in this age. 
The track of a Trilobite, Climatichnites, is shown by a cast in 
Case I A. Worms are represented by the borings and tracks of 
Scolithus. The Honey-comb Corals by Favistella, Graptolites 
by several g^ntxdi—Diplograptus, Climacograptus, etc. These 
are hydroids, the delicate plume-like nature of whose remains has 
given them their name, which is derived from the Greek word 
meaning “to write.” They are common fossils of this era. 
Sponges are represented by Receptaculites. 
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. 
Cases 2A, 15, O, I>, E, F. — Fossils illustrating the life 
of the remainder of the Silurian age, arranged according to per- 
iods in chronological or stratigraphic order. Only the more typical 
and abundant forms will be mentioned here. Plants, represented 
by large slabs of Arthrophycus and Bythotrephis, These are gen- 
erally supposed to be imprints of the leathery stems of seaweeds, 
but by some are thought to be markings of worms. Stems and 
bodies of Cxmoidj^—Glyptocrinus, Agelacrinus, etc. These are 
the most abundant Echinoderms of the early seas. Mounted upon 
a jointed stem and with many branching arms, they well deserve 
the name of Sea Lilies. Cup corals — Eridophyllum, Chain Corals, 
represented by Haly sites. 
Ordovician Trilobites — Asaphus, Illaenu'^, Dalmania. 
Many genera of Brachkopods, of which the following exist to 
the present day, and may be seen in the Department of Zoology. 
Hall 2 ^^— Lingula, Rhynchonella. Brachiopods are sometimes 
called lamp shells, on account of their resemblance to a Roman 
lamp ; the two valves of the shell are unequal in size, and the 
beak of the larger curls over on that of the smaller. Though 
found only in small numbers at the present day, they were in 
Silurian times the most abundant and characteristic form of 
marine life. They are allied to the Worms in structure. 
The Gasteropods, or univalve mollusks, are represented by 
