DEPARTMENT OF GEOLOGY 21 
degree from those of Carboniferous times, as may be seen by 
comparing the specimens of the two periods. 
A portion of a trunk of a tree of the Carboniferous period is 
shown in a floor case. This trunk is about two feet in diameter 
and the portion shown is six feet in height. On the wall an oil 
painting represents a forest of the Carboniferous age, with Ferns, 
Clubmosses, Equisetae, etc., grown to the height of forest trees 
of the present day. 
Triassic Period. — This period is the first of the Mesozoic era 
or Age of Reptiles. The land plants of the period are illustrated 
by series of impressions of the leaves of Pterophyllum, a Cycad, 
and stems of EquisetufH, a form allied to the modern Horsetails. 
Sponges are represented by Stellispongia and Corynella. 
Crinoids by Encrinus, and Sea-urchins by detached spines of 
Cidaris. 
Mollucscs of this period assume a decidedly modern appear- 
ance. This is illustrated by Lima, Pleuromya, Nucula, Myo- 
phoria and Modiola of the Pelecypods and Monodonta, Holo- 
pella, and Murchisonia of the Gastropods. Two new types of 
Cephalopods are shown. Ceratites has serrated suture lines 
and Arcestes and Rhacophyllites are true Ammonites having the 
complex lobed sutures. 
Pemphix is a crustacean of the type of the modern lobster. 
Triassic fish are illustrated by the teeth of Ceratodus and 
nearly complete specimens of Ischypterus and Samionotus. 
The huge frog-like head of Labyrinthodont shown by a cast 
is that of an Amphibian, and the Reptiles of the period are rep- 
resented by a cast of a head of Belodon, an ancient crocodile. 
Hall 35. 
This hall contains two somewhat distinct series, one intro- 
ductory to the study of fossils in general, the other, fossils of the 
Mesozoic era. 
Entering the hall from the West Court, the three wall cases 
on the right are devoted to the introductory series. The first 
two of these show a comparison of ancient and modern forms. 
Beginning with the lower orders of life, there are shown, for ex- 
ample, sponges which have lived at different periods of the 
earth’s history, and a modern sponge for comparison; while in 
succession Corals, Crinoids, Brachiopods, Articulates, and Verte- 
brates are similarly illustrated. 
