616 PROCEEDINGS Of THE GEOLOGICAL society. [June 22, 
cylindrical pieces deeply channelled on one side indicate the presence 
of the ventral set common in all Plesiosawrv. 
Breast and Shoulder-girdle.—The large flat bones, which can belong 
only here, differ so greatly from those of known Plescosauri, that the 
only ones the determination of which can be looked on as at all certain 
are the coracoids (Pl. XLI. fig.5).: These are joined firmly together 
by avery stout median border, and form a strong flattened beam 
lengthened transversely to the axis of the trunk, attaining in this 
direction a maximum diameter of 20 inches at the lower end of the 
glenoid cavity, and one of 18 inches at the upper end of this articular 
surface. Each coracoid, then, is an oblong plate having a very short 
sutural median border which ties it to its fellow, and a gently con- 
cave anterior border decreasing in thickness from the outer end (where 
it contributes to the scapular articulation ?) towards the middle, from 
which it again increases to its inner end, where the two coracoids 
meet in a remarkably strong non-articular projecting boss(@). Only 
a small piece of the natural posterior edge remains. It shows that 
this border curved inwards from behind the glenoid cavity towards 
the median line. How far the bone may have extended in this di- 
rection cannot be told; but, from the inclination of its ventral and 
dorsal surfaces towards each other, the mesial extension backwards 
would seem not to have been great. The outer border of the cora- 
coid is stout; it bears a large, hollow, oval articular surface (the gle- 
noid cavity, fig. 6, a), and in front of this a smaller trihedral surface, 
presumably for articulation with the scapular (d). The dorsal (?) 
surface of the coracoid is slightly smuous. The ventral surface has a 
deep hollow just behind and parallel to the anterior border of the bone. 
A stout ridge sweeping from the median boss on the anterior border 
outwards to the glenoid border, divides this hollow from another 
triangular hollow, which lies between this ridge and the median 
crest. Below*the outer end of this transverse ridge the ventral 
surface is convex from before backwards, and nearly plane trans- 
versely. 
Limbs.—Of the four principal limb-bones the left pair are nearly 
perfect ; my description is taken from these. One is rather shorter 
than the other; and this I assume to be the humerus, because in 
those Plesiosaurs in which there is any difference in the lengths of 
the humerus and femur the former is the shorter bone. In our Ple- 
siosaur the humerus (fig. 1) is also stouter than the femur. Its length 
is 203 inches. Its proximal half is very massive and of a subcylin- 
drical figure, while the distal half is expanded and flattened. The 
preaxial border (c) is nearly a straight line, broken both at the middle 
and towards the distal end by a slight excursion. The postaxial 
border (d@) in its proximal 12 inches is nearly parallel to the preaxial 
one ; but beyond this it sweeps backwards in a long curve and makes 
with the distal border a great wing, much larger relatively than that 
of typical Plesiosawri. The contour of the distal border (6) is formed 
by two slightly incurved lines which meet in a wide angle placed 
rather behind the axis of the bone. The postaxial division, which 
is much the longer, is, unfortunately, incomplete. This end of the 
