618 PROF, H. G. SEELEY ON THE DINOSAURIA OF 
Caudal Vertebre (fig. 5, p. 620).—The tail appears to have com- 
prised three types of vertebree. Of the earliest caudal there is one, of 
the middle caudal four vertebre, and of the later caudal region five. 
To these I have added provisionally two later caudals in the same 
condition of mineralization and of similar size, also from the Trump- 
ington pit, which show exactly the same characters, but were found 
subsequently. 
The first caudal is distinguished by a short deep centrum with a 
rounded visceral surface, flattened articular ends, no cheyron bones, 
small neural arch, and apparently poorly developed transverse pro- 
cesses, Which are abraded. The centrum is about 14 inch long, less 
along the neural canal and more at the inferior border. ‘The arti- 
cular face is 13 inch deep in front, and, as preserved, of the same 
width, though originally wider. A transverse depression runs across 
it in the middle so as to divide the surface into superior and inferior 
portions meeting at a slight angle. The neural canal appears to 
have been about 4 inch in diameter. The neural arch, as preserved, 
extends the whole length of the centrum, is depressed in front, and 
appears to have been fractured at its upper and hinder prolongation. 
All trace of the transverse process is removed by abrasion ; it was 
given off on a level with the base of the neural canal. ' ; 
The four middle caudal vertebree successively increase in length, 
have the sides of the centrum compressed, and the base narrow and 
rounded, largely encroached upon by the facets for the chevron 
bones. These vertebrae have strong transverse processes given off, 
so as to extend outward and a little forward. These transverse 
processes are flattened and apparently hollow, like the rest of the 
neural arch, and perhaps the body of the centrum. They rapidly 
become small, and in the fourth are reduced to transverse ridges 
which are already below the level of the neural canal. The first 
centrum, as preserved, is 14% inch long. The posterior articular 
face of the centrum is decomposed, and the anterior face obscured 
with matrix; but the facet for the chevron bone is a large equi- 
lateral triangular area with rounded angles, about 58, inch long. 
The space is concave, as though the bone had decomposed; but the 
decomposition does not extend onto the rounded articular margin 
of the centrum. ‘The depth of the centrum from the base of the 
neural canal is rather less than 14 inch. The space between the 
two facets for the chevron bones on the base of the centrum is less 
than 35, inch long. The transverse process is about ;%,; inch thick 
and 5, inch wide, 1 inch from inner border of the neural canal ; itis 
directed slightly upward, and its hinder margin inclines forward. 
The sides of the centrum are flattened, though slightly convex from 
above downward, and fairly concave from side to side. In the next 
caudal the centrum is 2 inches long at the base. The posterior 
articular surface is flat and subtriangular, 17 inch broad and about 
the same depth, with straight converging sides, which are truncated 
inferiorly by the large facet for the chevron bone, which is nearly 
75 inch long. The transverse processes are more nearly horizontal, 
but are broken abruptly ; the neural arch appears to have the lamin 
