340 Transactions. — Geology. 



specimen, are cylindrical, the most anterior being tlie 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 I'O 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 '1 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 sui'face are two pairs of small foramina. 

 The abdominal ribs are irregular in shape, tapering to both ends, and bcoind 

 together, ia 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, Q x Q 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. 1 c? is a vertebra found by Dr. Haast in a soft clay matiix, at the 

 Cheviot Hills, along with the paddle of Mauisaurus (8 a), but is placed here 

 on Account of its remarkably Plesiosauroid character, the neural arch showing 

 a distinct 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 



