24 



RECORDS OF THE AUSTRALIAN MUSEUM. 



II. — The Reptile Remains. 



To return to Messrs. Tweedie and Wollaston's reptile, Cimolio- 

 saurris IPAicoscopelus, the remains that can be satisfactorily deter- 

 mined from the mass of opalised material are as follows : — 



17 Cervical vertebrae, usually fragmentary. 

 2 Humeri. 

 4 Teeth. 



Rib fragments (numerous). 



Phalanges (numerous). 



The absence of the skull practically bases systematic determina- 

 tion on the vertebra? and teeth, hence the following facts in the 

 first place lead to the conclusion that it is a Sauropterygian : — 

 (1) the vertebrae are amphicoelus ; (2) the single costal facets of 

 the cervical vertebrae are entirely on the centra ; (3) each rib 

 articulates to a single vertebra ; (4) the epiphyses of the humeri 

 are enlarged ; (5) the teeth have more or less curved and sharp 

 crowns with fluted enamel. 



In the second place the form of the cervical vertebrae, and the 

 absence of a foramen in the humeri indicate the Plesiosauridaj as 

 the family to which these remains should be referred ; whilst 

 within this family the complete anchylosis of the neural arches 

 and cervical ribs to the centra, single costal facets on the cervical 

 vertebrae, and the slender and non-carinated teeth point out 

 Cimoliosaurus, Leidy, as the natural resting place of this reptile 

 from White OliflTs Opal-field. 



The cervical vertebrae are much elongated between their dorsal 

 and ventral extremities. They vary in size, as usual, according 

 to their position in the whole series, but the measurements of 

 three of the more perfect and typical are as follows : — 



The measurements are in inches and parts of inches. 



