340 T'ransactions.—Geology. 
specimen, are cylindrical, the most anterior being the largest, viz., 9 inches in 
length by :8 inch in diameter. They are closely packed, and, from their 
irregular curvature, seem as if they had been soft and flexible at the time 
they were imbedded in the calcareous mud. The largest caudal centrum has 
its transverse diameter 2 inches, and its vertical diameter 1:5 inches. The 
articular surfaces are nearly flat, with obtuse margins, and a distinct central 
pit. Their antero-posterior length is ‘8 inch, with a single inferior venous 
foramen. Similar centra occur, of various sizes down to ‘7 inch transverse 
diameter. None of the vertebral centra have attached processes, but some have 
distinct pits, to which the neural arch had its attachment. The dorsal centra 
are slightly longer, being 1:3 inches, and have a distinctly constricted 
form, their articular surfaces being a full oval, 2:3 inches by 1:6 inches, 
with sharp edges. On the ventral surface are two pairs of small foramina. 
The abdominal ribs are irregular in shape, tapering to both ends, and bound 
together, in groups of two or three, by their middle. Their greatest length is 
10 inches. 
The femur is 7 inches in length, proximal end rounded, 2:5 inches in 
diameter, distal end flattened and expanded to 4:5 inches. The pubic bone is 
rhomboidal, slightly concave, 6 x 6 inches, with only one well-marked 
elongated articular margin 3-5 inches in length. The ischium, of which only 
one is present, is more concave on the inner than the exposed surface, 2 inches 
wide at the articular extremity, 4-5 inches at the mesial, and 6 inches in 
length. The ilium has an irregular conical form, tapering, and slightly 
curved; its length is 4 inches, and its articular end, which is convex, is 
2 inches in diameter. The paddle bones are flat, with slightly concave surfaces, 
and irregular outline. The phalanges are cylindrical, and much constricted 
in the middle. 
Although the dimensions differ from those of the bones described by 
Professor Owen, which are common to the two specimens when allowance is 
made for the immature condition of the Amuri specimen, there is sufficient 
evidence to warrant their being placed in the same species. The characters on 
which I place most reliance are the coprolite-like form of the ribs and the 
silky texture. 
No. 1d is a vertebra found by Dr. Haast in a soft clay matrix, at the 
Cheviot Hills, along with the paddle of Mawisawrus (8 a), but is placed here 
on account of its remarkably Plesiosauroid character, the neural arch showing 
а distinet suture, though perfectly anchylosed to the centrum. This suture 
divides the articular surface for the head of the rib into two rough facets, the 
upper on a short transverse process, and the lower on the side of the centrum. 
The proportional length of the centrum of this vertebra exceeds that of any 
other Plesiosauroid in the collection, as will be seen from the following 
