356 Transactions. — Geology. 



Mauisatmis haastii ; but both of these have the articular sur- 

 faces flat, while in P. mackayi they are said by Sir James 

 Hector to be "quadrate, not circular,"''^ which is quite dif- 

 ferent from the present specimen. Lastly, M. haastii has a 

 very different coracoid and humerus, while M. latibrachialis is 

 only known by its humerus, which appears to differ much 

 from our animal. It is therefore necessary to make a distinct 

 species of the present specimen, and I have given it the name 

 of caudalis, in allusion to its long and powerful tail. Mr. 

 E. Lydekker has referred all the New Zealand Cretaceous 

 sauropterygians wath which he is acquainted to Leidy's genus 

 Cimoliosaunis,]: because the vertebrae seem to resemble closely 

 those of C. constrictus and G. lAanus. Cimoliosaurus is also a 

 genus which ranges from Middle Jurassic to Upper Cretaceous, 

 while Plesiosaurus, as now restricted, is found in Europe only 

 in the Ehaetic and Lower Jurassic. The principal generic 

 character of Cimoliosaurus is the shape of the scapula, and, 

 although this is not yet known in any of the New^ Zealand 

 species, I think it most prudent, for the present, to follow Mr. 

 Lydekker, and I therefore call this saurian Gimoliosa^irus 

 caudalis. 



Desceiption. 

 Vertebrce. — The neck is entirely missing. A row of eleven 

 dorso-lumbar vertebrae exhibit their ventral sides only ; the 

 transverse processes, zygapophyses, and neural arches being 

 buried in the matrix. However, a fragment can be removed 

 which enables the centrum of the eighth of the series to be 

 accurately measured. These measurements are as follows : 

 Antero-posterior length, 48mm. (l-9in.) ; length at middle of 

 cups, 39mm. (l-5in.) ; transverse breadth of articulating sur- 

 face, 65mm. (2-6in.) ; height of articulating surface to bottom 

 of neural canal, 55mm. (2-2in.). The transverse breadth at 

 the middle of the centrum is 56mm. (2-2in.). There are two 

 pairs of venous foramina on the ventral surface of each ver- 

 tebra. The outer pair, wdiich are the larger, are about 33mm. 

 or 34mm. apart, and the inner about 20mm. apart. They are 

 not situated in any cavity, nor are they bounded by any mark, 

 but the ventral surface of the vertebrae is smooth and rounded. 

 The tail probably exceeded the body in length. As at present 

 displayed there appear to be fourteen vertebrae, but it is only 

 the last seven which can be accurately measured. Of these 

 the antero-posterior length is 34mm. in the most anterior, and 

 28mm. in the most posterior ; while the length at the centre 

 of the cups is 25mm. and 22mm. respectively. The transverse 

 diameter of the articular surface is 6imm. in the most anterior 



* Loc. cit., p. 345. 



t Catalogue of the Fossil Rcptilia in the British Museum, vol. ii. 



