“THE CAMBRIDGE GREENSAND, - Hite 613 
side to side posteriorly is 1,2, inch, from front to back at the ex- 
ternal border 1%; inch, and from the cnemial crest to the inner 
posterior border 1,8, inch. The two posterior angles of the bone 
are rounded, and the cnemial crest, which is gently concave in the 
outline of its length, becomes more compressed proximally. 
The distal fragment becomes flattened in front and convex from 
side to side behind, with the fibular side flattened and front inner 
margin angular. The bone curves a little forward towards the 
distal end. Its measurement from side to side is reduced to 58, inch, 
and from back to front to $3 inch. The medullary cavity is very 
large ; its wall is thinner in front than elsewhere. 
The tibia was more slender than might have been expected, 
and appears to have been of about one fourth the size of the tibia 
of Hadrosaurus figured by Leidy. It closely resembles in form the 
same element of the skeleton in some Dinosaurs from Gosau. 
Metatarsus.—The metatarsus is represented by the proximal halves 
of three bones somewhat rubbed, and a distal end of another. The 
fractures show them to have had medullary cavities ; but they are 
too imperfect for description. There is also a phalange (Pl. XXXY. 
fig. 10). 
Part LY. 
On the Axial Skeleton of Eucercosaurus tanyspondylus, Seeley, a 
Dinosaur from the Cambridge Greensand, preserved in the Wood- 
wardian Museum of the University of Cambridge (figs. 4 & 5, 
pp. 616, 620). 
INTRODUCTION. 
The remains of a large land-animal, for the reception of which it 
becomes necessary to institute the genus Hucercosaurus, are limited 
to an associated series of nineteen vertebra and a neural arch, ob- 
tained from one of the more recently opened workings in the Upper 
Greensand, at Trumpington, near Cambridge. The state of pre- 
servation is not very satisfactory, the bones being often incrusted 
with phosphate of lime, and several of them considerably decom- 
posed, as the consequence of long maceration. Some of them have 
also been a little worn, and a few broken, during their discovery, by 
the picks of the excavators. 
There is no indication of the skull or neck; but both may be 
inferred to have been small, since the four dorsal vertebre preserved 
show a considerable and decreasing difference in size towards the 
neck. At first sight there may seem to be just a possibility that 
the eighth vertebra may not belong to the same animal ; but against 
that suggestion is the evidence of similarity of form and similar 
condition of preservation. 
. Lam led, by the forms of the vertebre, to anticipate that the 
animal carried itself in a more or less erect position, supported on 
the hind lmbs, and that, following the usual osteological law ex- 
emplified in the vertebral column of man, the growth of the lower 
