1872.] 425 [Cope. 
pits and grooves, which radiate from the base at the (?) front of the ridge. 
Length, M. .185; width, .21. 
The lateral dermal bones preserved, are two entire, and large parts of 
one or of two others. They have an irregular oval outline and are slightly 
dished on the inferior surface or that next the ribs. The upper surface 
is more convex longitudinally, from the thickening of the bone. The 
margins are irregular from the projection of many digitations. Some of 
these are broad and flat, others are narrow. They are frequently two 
deep, and the fissures separating them occasionally extend far towards 
the middle of the bone. The convexity assumes the form of a low ridge 
towards one end of the bone. At the point where this reaches the mar- 
gin, the latter is in all the four plates, thickened, and composed of several 
layers of packed osseous radii. When found, the ribs laid across these 
shields ; one of them occupying the position of a radius to one of them. 
These shields are much larger than the marginal bones, 
M. 
lhength ‘No. 10 (21 in¢hes).. v.72 50.0705, Hebei. 0.585 
Width f (broken) yt 0 oa Wale 6 etal 4400 
dnicknessabamiddler wc 000. . ae eae eae, 014 
hemath> “INOnOC ant ee ae 530 
Width ‘* (much broken)...... PO, A 580 
Thickness at the middle....... aes eA TO Gn .013 
The lengths and breadths given are a little below the truth, owing to 
the loss of the exceedingly thin margin. 
Turning to the endo-skeleton, the vertebra deserve mention. There are 
more or less complete examples of five of these : in two, both centrum 
and neural arch ; in two, neural arch ; and in one, centrum, are preserved. 
These have been recognized chiefly by their neural arches, which are sep- 
arate. They are in form something like an X, the extremities of the 
limbs carrying the zygapophysal surfaces. The only point of contact 
with the centrum is a wide process which stands beneath the anterior 
zygapophysis, and spreads out foot-like obliquely forwards and outwards, 
to beyond the line of its anterior margin. Its surface extends nowhere 
posterior to the surface of zygapophysis above it, but a little further 
inwards. Its outer margin rises ridge-like to the under side of the neural 
arch, and each one forming a semi-circle forms the boundary of the neu- 
ral canal, and turning outwards forms the inner boundary of the posterior 
or down-looking zygapophyses. The space between these apophyses is 
roofed over, so as to produce a shallow zygantrum, which, however, only 
seems to roof over the deep emargination of the neural arch of the verte- 
bra immediately following. The anterior zygapophyses are often broken 
away, so that the neurapophysial supports look like the missing pair, 
when the difficulty ensues that both pairs look downwards. The top of 
the neural arch is in two cases broad and flat ; in two others there is an 
obtuse keel. 
The centra apart from theix arches are puzzling bodies, especially since 
A. P. S.—VOL. XII.—3B 
