‘Hector.—On the Fossil Reptilia of New Zealand. 345 
peculiar character of the species. Transverse diameter of the centra 4 inches, 
vertical diameter 355 inches, antero-posterior length 2 inches. The neural 
spines are 1-7 inches in antero-posterior width, 4:5 inches long, leaving only a 
very narrow space between, and this is deeply notched by a bold zygapophysial 
articulation 1:3 inches in depth. 
No. 5 b. —Is a slab with several vertebre, and also obscure fragments of 
the lower jaw, among which is a single tooth in sit (Pl XXIV., fig. н). 
This tooth is 2-2 inches long, and ‘3 inch in greatest diameter, which is at the 
base of the crown, at 1 inch from the tip. It is a curved, flattened, produced 
cone, without any sign of a sharp ridge like that seen in the supposed tooth of 
Mauisaurus, to which, however, the species has some affinity, but is easily 
distinguished by the shorter vertebre and the quadrate, not circular, form of 
the articular facets. 
6. PLESIOSAURUS MACKAYII, n. sp. 
This species is not unlike the last described in the form of the tranverse 
section of the centra of the vertebra, but their length is very different, being 
almost equal to the vertical diameter, as in Jfawisaurus. But it is distin- 
guished readily from that genus by the form of the humerus (ба), which i$ dilated 
at the distal end with a rounded articular extremity, and at the proximal end 
is feeble. The shape is somewhat prismatic, but the bone has been a good 
deal water-worn before being imbedded in the matrix. The clavicular bone 
is slender, with a well-marked oblong articular surface. A fragment of the 
coracoid bone shows this apparatus to have been very powerful, the width 
being about 7 inches, with a very strong symphysial surface. The articular 
surface at the angle of the bone for receiving the humerus is elongate and 
narrow, being 1:7 inches wide at the middle, and tapering both ways, to a 
length of 4 inches. The vertebral centra preserved, which belong to the 
dorsal region, have the following dimensions :—Antero-posterior diameter 3 
inches, transverse 4 inches, vertical 3:2 inches. The humerus measures 13:5 
inches in length, and is 8 inches wide at the dilated extremity. 
7. PoLYCOTYLUS TENUIS, n. sp. 
This genus, according to Professor Cope, has close affinities to Plesiosaurus, 
but is distinguished by short deeply-concave vertebral centra, the concavity 
not, however, being of an open conic form, as in Jehthyosawrus, but distinctly 
flattened at the fundus. The limb bones are remarkable for their size com- 
pared with the vertebral column, indicating powerful natatory capacity. To 
this genus, under the above specific name, I provisionally refer the speci- 
mens marked 7 a, b, c, and d, all of which were obtained at the Amuri 
Bluff The first consists of two slender paddle bones and one centrum, 
probably cervieal. The length of each paddle bone (humerus!) is 9 EE. 
BZ 
