342 Transactioiis, — Geology. 



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 mo)-e 

 circular in form, the transverse and vertical diameters being 35 and 2 '8 inches 

 respectively, while the length is nearly 2 inches. 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 

 Pleiosauriis lyortlandicus, in which the small crateriform pits of the articular 

 surface are shown ; but their character is common to Pleio- and Plesio- 

 sauTus." 



No. 2 6 is a slab showing a humerus and a few bi'oken ribs, identical with 

 the above in their characters, obtained at the Amari Bluff". 



No. 2 c shows a few cervical vertebrae obtained by Dr. Haast at the same 

 locality, which serve to confirm the occurrence of this species at both these 

 localities. 



No. 2 d, in the Canterbury Museum, are a few vertebrae, a coracoid bone, 

 and humerus, from the Waipara, which also belong to this species. 



