Hector.—On the Fossil Reptilia of New Zealand. 343 
3. PLESIOSAURUS ноорп, Owen. Geol. Mag., 1870, p. 51. 
Professor Owen named this species from the drawing of a single cervical 
vertebra (3 d) obtained by Mr. Holmes at Waipara. These vertebra, of 
which several other specimens have since been obtained (both from the 
Waipara, 3 0, and the Amuri Bluff, 3 c and 3 d), are easily distinguished by 
their peculiar characters, which are thus described, from the first discovered 
specimen, by Professor Owen :—* It is broad and flat on the under surface of 
the centrum ; the sides also of which, between the terminal artieular surface, 
are more flattened than usual, and converge towards the neural surface, giving 
somewhat of a triangular figure to the vertical transverse section of that part. 
The pleurapophyses come off from the lower part of the sides, and are 
confluent therewith, like transverse processes. The characteristic pair of 
venous foramina open upon the middle of the under surface. This vertebra 
most resembles one from the bone bed of Aust-Cliff, near Bristol, described in 
my * Report on British Fossil Reptiles, 1839, p. 78, and referred, with a note 
of interrogation, to the Plesiosawrus trigonus of Cuvier. The articular surface 
of the centrum is moderately concave, with a transversely oblong depression in 
the centre, and the margin rounded off. The neural arch is anchylosed to the 
centrum. The neural canal is contracted, as usual in cold-blooded air- 
breathers, and shows the ordinary proportion of that in Plesiosaurus. The 
pleurapophyses are short and thick; the fore and aft diameter of their base 
equals two-fifths of that of the entire centrum ; they are somewhat inclined 
downward. A distance of twice their vertical basal diameter intervenes 
between them and the anchylosed base of the neurapophysis. 
* This vertebra gives the following dimensions :— 
Length of centrum .. 2 inches 1 line. 
Breadth of articular end ‘of centru 6 2 0 
Height of articular end of йене, at middle Ки 1 
“'Тһе New Zealand specimen shows an exceptional form among the 
extensive series of modified Plesiosaurian cervical vertebrze already defined or 
recognized. Moreover, it is that form which hitherto, from British deposits, 
has not been met with associated with other parts of the frame, yielding the 
characters of proportionate length of neck ; proportion of head to body; shape 
and number of teeth; form, structure, and proportions of limb-skeletons, 
either in relation to the trunk, or in that of the pectoral pair to the pelvic 
pair. In short, materials have been wanting for assurance that the degree of 
modification of the cervical vertebra may not have been associated with so 
much modification of the rest of the skeleton, as to warrant a generie section 
of Sauropterygia, or a subgeneric one in the Plesiosauriah family." 
The proportions of the specimen given above agree well with the cervical 
vertebre since obtained, although the actual dimensions vary somewhat. Thus, 
