342 T'ransactions.—CG eology. 
diameter. They are deeply excavated beneath, with two venous foramina. The 
articular surfaces are elongated transversely, forming a constricted oval, and 
only moderately concave, with rounded margins. ‘The dorsal centra are more 
- circular in form, the transverse and vertical diameters being 3:5 and 2:8 inches 
respectively, while the length is nearly 2inches. They are much constricted on 
each side, and expanded at the ends to form a smooth, slightly concave 
articular surface, with a central tubercle :5 inch in diameter. The neural 
processes are detached, their height, including the neural canal, being 4:5 
inches. The lateral processes are flattened, but expanded at the tip, to form 
roughened circular facets for the rib articulations. Their length is 3:5, and 
width 1:3, inches. The ribs, twelve in number, are well preserved. They are 
flattened, with sharp anterior margins, slightly expanded towards the vertebral 
column, then constricted, and flattening out again at the centre, where they 
make an obtuse forward angle. The length of the first rib preserved is 
12 inches, and of the eighth, which is the largest, 19 inches. The total 
length of the specimen is 3 feet, and, judging from the proportional length of 
the thorax in the long-necked Plesiosaurs, must have belonged to an animal 
at least 10 feet in length. 
A portion of a humerus, belonging to this specimen, was also described 
(from a drawing) by Professor Owen, who points out that “it shows the 
hemispheroid articular head, coarsely pitted by characteristic circular depres- 
sions, with slightly raised margins. The degree of contraction of the shaft to 
the broken, and the indicated retention of a subcylindrical shape of shaft, 
are incompatible with any known modification of an Ichthyosaurian humerus 
or femur. These are more angular and transversely oblong at the proximal 
end, and more rapidly compressed and expanded in the distal one, in the fish- 
like sea-lizard. The fragment of limb bone in the Museum at Wellington is 
plainly Plesiosaurian. The long diameter of the head of the bone is 3:5 inches, 
the short diameter 3 inches. The peripheral contour is flatter or less convex 
on one side than the other, as it is in the same part of the femur of 
Pleiosaurus portlandicus, in which the small erateriform pits of the articular 
surface are shown; but their character is common to Pleio- and Plesio- 
saurus." 
No. 2 b is a slab showing a humerus and а few broken ribs, identical with 
the above in their characters, obtained at the Amuri Bluff. 
No. 2 c shows a few cervical vertebre obtained by Dr. Haast at the same 
locality, which serve to confirm the occurrence of this species at both these 
localities, ғ 
No. 2 d, in the Canterbury Museum, are a. few vertebra, a coracoid bone, 
and humerus, from the Waipara, which also belong to this species. 
