MONOGEAPH 



ON THE 



FOSSIL CHELONIAN REPTILES 



OF THE 



WEALDEN CLAYS AND PURBECK LIMESTONES. 



ORDER— CHEL ONI A. 

 Family— PALUDINOSA. 

 Genus — Pleurosternon/ 



In acquiring the requisite materials for the present Monograph, I have had under 

 examination numerous Chelonites from the Wealden series, the majority of which, as 

 in most of the secondary rocks, were more or less fragmentary; indicating, indeed, 

 with sufficient certainty, the order of Reptiles to which they had appertained, but not 

 so perfect as to yield the characters required for determining the family of Chelonia to 

 which they had belonged, much less their relations to the known species of tertiary 

 and existing Tortoises and Turtles. 



From the above series of Wealden Chelonites, I have selected for description and 

 delineation those specimens which seemed best to illustrate the nature of the 

 house- carrying Reptiles of the period; and propose to commence with the more 

 perfect specimens which have been extracted from the fresh-water limestones of the 

 Purbeck beds. For the opportunity of examining and figuring the best preserved ex- 

 amples of this kind, I am more especially indebted to Wilham Cunnington, Esq., of 

 Devizes, and to Charles Willcox, Esq., M.R.C.S., of Swanage, Dorsetshire. 



' Derivation — TrXevpo*' a rib, oTi^vov the breast-bone. 



