Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/639

Rh rather smaller. The nutritive foramina become small circular pits rather further apart. In all about 40 vertebræ have been collected, of which about 14 are dorsal.

So far as can be judged from the size of the vertebræ, this species was rather larger than the Elasmosaurus platyurus of Prof. Cope, and is therefore the largest long-necked member of the order Plesiosauria which has been discovered.

Since different writers have different methods of fixing the limits of the several regions of the vertebral column, which results in an undesirable confusion of characters of the species described, I venture to offer the following diagram as a convenient guide to uniformity in this particular, and as representing the characters of the divisions of the vertebral column which I have described in this and other

Plesiosauria, in so far as they depend upon the position of the articulation for the rib upon the centrum, or upon the neural arch.

Many of the dorsal ribs of Mauisaurus Gardneri have a strong lateral crest at the proximal end, which makes the bone subtriangular in section. The fragments have a considerable curve; but none are sufficiently perfect for description.

The bones of the pectoral arch are unfortunately imperfect. A fragment of a coracoid is 13 inches long, and 10 inches wide, as preserved; it does not show generic characters. The bones met in the median line anteriorly, as usual, but appear to have diverged posteriorly. Some fragments of scapula (?) appear to be not unlike the scapula of Murænosaurus, but are imperfectly preserved. Dr. Hector mentioned to me that he thought it possible for the scapulæ of Mauisaurus to have been convergent forward, and that they may not have been directed outward as in his figure (Trans. New-Zeal. Inst. vol. vi. 1874, pl. xxix.).

The humeri and femora have both been found. From the great size of the neck-vertebræ, and the decrease in size of the dorsal vertebræ, as they approach the sacral region, I am disposed to conclude that the humeri were larger than the femora. The humerus is 13 inches long and imperfect proximally. Midway between the proximal and distal ends the transverse width of the shaft is 7 inches. At about 4 inches from the proximal end the shaft is 3$3⁄4$ inches thick; but