27 
Lamelhbranchs and Gasteropods, illustrated by many speci- 
mens, mostly of modern types — Ostrea, or oyster, of many and 
curious shapes; Pecten, Vola, Exogyra, Gryphaea, etc. 
Among bivalve mollusks the order of Rudistes is unique, 
and characteristic of this period. In shells of this order one 
valve is enormously enlarged, and somewhat funnel-shaped; the 
other valve is small and acts as a lid — Hippurites, SpheruUtes, 
Radiolites, Inoceramus also belongs to this order, and some- 
times reaches enormous size. 
FIFTH CASE, RIGHT. — Cretaceous vertebrates. The spec- 
imens include remains of large carnivorous fishes of the Cre- 
taceous seas of Kansas, and of ancient sea serpents {Plate- 
carpus), 
Tertiary fishes. The specimens include a fine series of 
beautifully preserved fishes from the Green River, Wyoming 
beds, also smaller species from Syria and France. They belong to 
the modern order of Teleosts or osseous fishes in which are in- 
cluded the perch, herring, etc, 
FIFTH CASE, LEFT. — Tertiary invertebrate fossils. Fla- 
bellaria, leaves of a palm which grew in the Eocene epoch near 
Green River, Wyoming. Also, leaves of Acer, or maple, and 
other trees of modern species. 
Such remains, with others that are found, indicate that a 
sub-tropical climate, like that of Florida, prevailed at this per- 
iod over the Northern United States. Even as far north as 
Greenland, the climate was so mild that cypress and cedar trees 
grew in profusion, 
Nummulifes . — These are abundant and characteristic fos- 
sils of this period. They are shells of a Rhizopod, which in 
Europe and Africa form limestomes many thousand feet in 
thickness. 
Among univalve mollusks many modern types will be rec- 
ognized — Turritella, Natica, Cerithium, S trombus, etc. 
SIXTH CASE, LEFT. — Vertebrate fossils of the Tertiary 
period. Fossil turtles are represented by carapaces from locali- 
ties in Nebraska, South Dakota, and South Carolina; also turtle 
eggs from France. 
The Cetacea, or whales, of this period, are illustrated by 
centra of vertebrae of the Zeuglodon. Remains of this whale 
are chiefly found in the Southern States. 
