A NEW DINOSAUR. 
133 
black soil, some rootlets actually being present in the interstices. Owing to- 
the effects of prolonged abrasion and weathering, large portions of the original 
contours have been lost. 
For convenience in description the specimens have been designated A, 
B, and C. (Reg. No. F2316.) 
DESCRiPTrcw. — Specimen A consists of the major portion of one centrum, 
with the lower part of the neural arch, and the fractured " cup of the- 
contiguous unit, which has fragments of its arch in the matrix above. In 
the more complete vertebra, the posterior part of the centrum has been shorn 
away, and the cross section of fracture shows within the thin walls a coarse 
mosaic of irregular cancel li enclosed by thin bony plates. These intersecting 
laminae form a labyrinth throughout the exposed transverse section of the 
centrum, but are most prominent where supporting the cortical walls. The 
canc-elli are wholly or partly infilled with a crystalline matrix of carbonate of 
lime (described elsewhere). 
The lateral Avails of the right side of the centrum have disappeared, 
but the anterior part of the left lateral surface is preserved, with an almost 
complete pleurocoele. This area has been largely freed from the matrix and 
exhibits important characteristics (Plate XV.). Of the actual walls of the 
inferior surface of the centrum only a small portion is preserved, but the 
general proportions are apparent. When viewed from below, it is seen that the 
body of the centrum is constricted and the lateral walls curve outwards 
anteriorly to the much larger rim of the " ball.” This constricted portion of 
the centrum, with its associated lateral cavities, is evidently fragile in 
comparison with the articular areas, for all of the specimens are fractured in 
this region. 
The dimensions of Specimen A are as follows : — Maximum length 1 (fl- 
inches (267 mm.) ; height 16J inches (413 mm.) ; transverse diameter lOJ- 
inches (257 mm.). 
Pleurocoele. — This is situated in the upper portion of the centrum 
and is well shown in Plate XV. This large lateral cavity is divided into an 
external and an internal portion. The former is a large horizontal oval recess, 
from which the matrix has been cleared, and at the bottom is a much smaller 
oval fenestra, the internal pleurocoele, which extends further into the centrum. 
The external recess is about 42 mm. in depth ; its antero-posterior diameter 
is approximately 90 mm., and its vertical height is 60 mm. The lower wall 
of this cavity forms an almost horizontal shelf, but, from the inner surface, 
the upper and anterior walls curve gradually outwards to the plane of the 
lateral surface. The matrix has been almost entirely cleared from the internal 
pleurocoele, the diameters of which are approximately 50 mm. by 30 mm.. 
This inner recess is divided into two portions by a thin vertically-placed bar 
of bone, situated at the anterior third. 
