338 Transactions.— Geology. 
PYTHONOMORPHA. 
Vertebre concave in front, and convex behind. Teeth firmly attached to 
the jaw ; never occur free in the matrix, except when broken off: 
f A—Luiopon. 
Dorsal vertebre subprismatic, cup and ball of equal diameter. Teeth conical, 
curved, with thick enamel, pulp cavity constricted at base. 
B—TANIWHASAURUS, 
Dorsal vertebra with the cup end expanded, and tapering obliquely to the 
ball end. Humerus very short, wide, and with powerful muscular crests. 
Teeth conical, with pulp cavity expanded at base. 
1. PLESIOsAURUS AUSTRALIS, Owen. Proc. Brit. Assoc., 1861, р. 122. 
As Professor Owen’s description of the specimens on which he founded this 
species is not accessible to many in the colony, I quote it at length. 
The specimens “ consisted of two vertebral bodies or centrums, ribs, and 
portions of the two coracoids of the same individual, all in the usual petrified 
condition of oolitie fossils. Their matrix was a bluish-grey clay-stone, effer- 
vescing with acid ; the largest mass contained impressions of parts of the arch, 
and of the transverse processes of nine dorsal vertebre, and of ten ribs of the 
right side, Portions of five of the right diapophyses and of six of the ribs 
remained in this matrix. The bones had a ferruginous tint, contrasting with 
the matrix, as is commonly the case with specimens imbedded in the Oxfordian 
or liassic clays. The impression of the first diapophysis and of its rib, 
show the latter to have been artieulated by a simple head to its extremity, 
as in the Plesiosaurus; but the succeeding rib had been pushed a little 
behind the end of its diapophysis, and the same kind of dislocation had 
plaeed the five following ribs with their articular ends opposite the inter- 
spaces of their diapophyses. The ninth rib had nearly resumed its 
proper position opposite the end of the diapophysis, but at some distance 
from it; the impression of the tenth rib shows: the normal relative 
position of tbe pleur- and diapophyses. The ribs are solid, of compact 
texture, cylindrical, slightly eurved, the fragments looking more like coprolites 
than bone; they are about an inch in diameter, with but small intervals 
of, say, one-third of an inch, slightly expanding as they recede from the 
transverse process, and slightly contracting to the lower end. The first, 
terminating in an obtuse end of 1 an inch diameter, is 7 inches long ; the 
second is 8 inches long; the third is 81 inches; the fourth rib is 9 inches 
long. The extremities of the others are broken off with the matrix. The 
separated fossils sent from New Zealand included the mesial coadjusted ends 
of a pair of long and broad bones, thickest where they were united, and 
