412 PLESIOSAURUS IN THE MESOZOIC ROCKS OF QUEENSLAND, 



is precisely what we have here, the diapophysis assuredly having 

 reached its definite elevation. Again, if I am right in conjectur- 

 ing that the two pieces of rib appertain to one, the sum of these 

 characters would seem to indicate the middle of the dorsal series 

 as the position to be occupied by the present bones when in situ 

 in the column. 



Little can be said as to the specific identity of these vertebrae. 

 The remains of two species of Plesiosaurus have been described 

 from Queensland: — 



P. macrospondylus, McCoy. — Cervical vertebrae with very 

 rugose articular surfaces to the centrum. 



F. Sutherlandi, McCoy. — 'Trunk' vertebrae, having the centum 

 2\ inches long, by 3| inches wide, by 2| inches deep. 



As regards the first of these vertebrae, they are, so far as 

 discovered, cervical, but if the dorsal are similarly rugose, the 

 bones now under description must be distinct. In connection 

 with P. Siithfrlandi, the word trunk would lead one to infer that 

 dorsal vertebrae are prol)ably meant, as distinct from cervical and 

 caudal ; if so, the measurements are quite different from those 

 of the present specimens. 



Several species have been described from the Mesozoic rocks of 

 New Zealand, by Sir R. Owen, F.R.S.,* and Sir James Hector, 

 F.R.S. ;t but I am unable to satisfy myself of the identity of the 

 present specimens with any of them. Two, P. Australis, Owen, 

 and P. crassicostatus, Owen, appear to be well known. The first 

 is distinguished by'the general character of its vertebrae ; those of 

 the second by the presence of a very large central tubercle. The 

 four others we are less acquainted with, and a comparison without 

 actual specimens becomes very dilficult. Two, P. Hoodi, Hector, 

 and P. Holmesli, Hector, are known only by cervical vertebrae; 

 whilst of the two others, P. Traversi, Hector, and P. Mackayi, 

 Hector, we are only acquainted with cervical vertebrae and poitions 



♦Report Brit. Assoc. 1861, p. 122; Geol. Mag. 1870, p. 52. 

 t Trans. N. Zealand Institute for 1873 [1874], p. 333. 



