146 
THE UPPER GALLERY. 
At the head of the staircase, on the western side, are some- 
remains of Ichthyosaurus , including a fine specimen from the- 
Lower Lias of Street, in Somersetshire ; and on the stairs of 
the eastern side, a Plesiosaurus from the same locality. The 
ichthyosaurus was a gigantic reptile of aquatic habit, furnished 
with a vertical tail, and with paddles resembling those of the 
whale, while it is known that some species had a triangular 
dorsal (in. It was a creature of great size, some specimens 
attaining to upwards of 24 feet in length. The plesiosaurus is 
another extinct aquatic reptile of large size, and furnished with 
paddles resembling those of the ichthyosaurus, from which it 
differed however in general form, its most distinctive characters 
being found in its comparatively small head and long neck. A 
head of Teleosaurus, a crocodilian form, resembling the recent 
gavial of the Ganges, is placed in Recess No. 3. 
A rich collection of Oolitic mollusca, excluding cephalopods. 
will be found in the Flat Cases 8 to 31, and the remaining^ 
invertebrates, including the corals, crinoids, sea-urchins, star- 
fishes, cephalopods and Crustacea, in Wall Cases 7 to 10 . At 
the head of the western stairs is a Case (C), specially devoted 
to the fine collection of Oolitic Trigonias, made by the late 
Dr. Lycett. Some well-preserved plant-remains from the 
Inferior Oolite, near Scarborough, principally ferns and cycads, 
are in Wall Case 7 , while the Purbeck cycad-stems, known to 
quarrymen as “ birds’ nests,” are in the lower part of the large 
Case (C) at the top of the staircase. The largest of all the Ammo- 
nites — Ammonites giganteus — from the Portland beds, is repre- 
sented by specimens near the stairs. The vertebrata of the 
Oolites are placed with those of the Lias — the two formations 
being often united under the name of the Jurassic system — in 
the Recesses 2 and 3. The remains of turtles from the Purbeck 
beds are here noteworthy ; but even more interesting are the 
mammalian relics, among which attention may be specially 
called to the unique specimen of Stereognathus from the Stones- 
field Slate, and the beautifully preserved jaw of Triconodon, 
from the Purbeck beds, presented by Mr. Henry Willett. 
The fossils of the Wealden beds, which are of fresh-water 
origin, find illustration in the Flat Cases 33 and 34, and the 
Wall Cases 3 and 10 . They include the remains of plants, 
mollusca, Crustacea, fishes, and reptiles. Among the reptilian 
relics the most notable are those of the gigantic dinosaurs 
(Gr. deinos , terrible), of which Iguanodon is the type. 
The marine beds of the Lower Greensand, the Gault, and the 
Upper Greensand, have yielded a rich fossil fauna, amply illus- 
trated in the Wall Cases 11 and 12 , and in the Flat Cases 34 to 
49. It is not unusual to associate the Lower Greensand with 
the Wealden beds, under the name of the Neocomian group — a 
name borrowed from the Latinised form of Neuchatel ( Neo - 
comum). Of all these Lower Cretaceous fossils, the most 
attractive, by the perfection of their preservation, are those of 
