26 
The specimens are chiefly from beds in England and Ger- 
many, and include many species. The series is one of the finest 
to be seen in any museum. 
The Pterosaurs, or flying reptiles, are illustrated by im- 
prints of wings of the Rhamphorhynchus, an animal not unlike 
the bat in appearance, and by casts showing remains of Ptero- 
dactyls, 
THIRD CASE, LEFT. — ^Jurassic fishes. Chiefly from the 
Solenhofen beds. 
FOURTH CASE, LEFT. — Fossils of the Cretaceous period. 
Here we find the first of modern plants, or Angiosperms. Im- 
prints of leaves are shown, many being modern genera, such as 
Sassafras, Populites, or poplar, Betulites, or birch, and Viburn- 
um, 
The localities illustrated are chiefly Kansas and Colorado. 
Casts, much enlarged from the original, illustrate the forms 
of Foraminifera, whose shells make up the vast deposits of chalk 
which characterize this period. 
Echinoids. — Ananchytes, Holaster, Toxaster, etc. These are 
free-moving forms in contrast to the stemmed so abundant in 
earlier times. 
FOURTH CASE, RIGHT. — Cretaceous fossils continued. 
Among Cephalopods are shown specimens of Nautilus of mod- 
ern type; also members of the Ammonite family, which take on 
various and intricate forms. The series of Placenticeras, an am- 
monite with coiled shells often two feet in diameter, is especial- 
ly worthy of note. The specimens are chiefly from the Bad 
Lands of South Dakota. Many varieties of shape are found 
among the Ammonites, from straight shells to hook-shaped, part- 
ly uncoiled spirals, spirals, etc. The genera are often named 
from their characteristic forms, some of them being as follows: 
Baculites, rod-shaped; Hamites, hook-shaped; Helicoceras, an 
open spiral; Scaphites, boat-shaped; Turrilites, tower-shaped. 
Agassiz describes these forms as representing the death con- 
tortions of this remarkable family. It is true that with this age 
this group, which had so long been one of the dominant types of 
marine life, became extinct, but the forms show progression up 
to the time of extinction, and not degeneration. 
