THE GEOLOGIST. 
ON THE REMAINS OF A PLESTOSAURIAN REPTILE (PLESIOSATT- 
RUS AUSTRALIS) FROM THE OOLITIC FORMATION IN THE 
MIDDLE ISLAND OF NEW ZEALAND. 
By Professor Owen, F.R.S., &c. 
The author, premising a quotation from his "Palaeontology," that "the further 
we penetrate into time for the recovery of extinct animals, the further we must 
go into space to tind their existing analogues and that " in passing from the 
more recent to the older strata, we soon obtain indications of extensive changes 
in the relative position of land and sea cited some striking examples in proof 
of these propositions from the reptilian class. The Mosasaurus of the creta- 
ceous series occurs in that series in England, Germany, and the United States. 
The Polyptychodon occurs in the same series at Maidstone and at Moscow. 
Toothless Lacertian reptiles have left their remains in triassic deposits at Elgin, 
in. Shropshire, and at the Cape of Good Hope. Dicynodont reptiles occur in 
the same formation at the Cape and in Bengal. The Plesiosaurus, with a more 
extensive geological range through the Jurassic or oolitic series, has left re- 
presentatives of its genus in those mesozoic strata in England, and at her anti- 
podes. Evidence of this extreme of geographical range had been submitted to 
Professor Owen by Mr. J. H. Hood, of Sydney, New South Wales, obtained by 
him from the Middle Island of New Zealand. This evidence 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 oolitic fossils. Their 
matrix was a bluish grey clay-stone, effervescing with acid ; the largest mass 
contained impressions of pares of the arch and of the transverse processes of 
nine dorsal vertebrae, 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 embedded in the Oxfordian or the liassic clays. The impression 
of the first diapophysis and of its rib show the latter to have been articulated 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 placed the five following ribs with their articular ends oppo- 
site the interspaces 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 the pleuro 
and diapophyses. The ribs are solid, of compact texture, cylindrical, slightly 
curved ; 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 half 
an inch diameter, is seven inches long ; the second is eight inches long ; the 
third is eight inches and a half ; the fourth rib is nine inches long. The ex- 
tremities of the others are broken off with the matrix. The separated fossils 
sent from New Zealand included the mesial co-adjusted ends of a pair of long 
and broad bones, thickest where they were united, and becoming thinner as 
they extended outwards, and also towards the fore and hind parts of the bone, 
both of which ends were broken away. On one side, the surface of the bone 
is convex lengthwise, and slightly concave transversely. On the opposite side, 
the contour undulates lengthwise, the surface being concave, then rising to a 
convexity, where a protuberance has been formed by ]3art of the coadjusted 
mesial margins of the bone ; transversely, this surface is slightly concave. A 
similar, but less developed, median prominence is seen at the middle of the 
medially united margins of the coracoids in the Plesiosaurus Hawkinsii, and I 
