O FOSSIL REPTILES OF DORSET. 



place it unmistakably with the Emydians. Found in the Middle 

 Purbeck-beds of Swanage. 



GENUS PELOBATOCHELYS, Seeley. 



PELOBATOCHELYS BLAKII, Seeley. 



This freshwater Turtle differs from Pleurosternon and Tretosternon 

 in the carapace, which is arched and rises to a median ridge ; also in 

 the cartilaginous space between the central and marginal plates. 

 Mr. Seeley considers it to be more closely allied to Palseonidus 

 from the Lithographic beds of Bavaria. Mr. Damon has a very 

 fine example of this newly described Emydian from the Kimmeridge 

 clay of Sandsfoot Castle, near Weymouth. The length of the 

 carapace is 26J inches, and its breadth 28J inches. A costal plate 

 at the broadest part of the carapace is six inches long and three 

 inches broad. The elevated ridge, which resembles the roof of a 

 house, has yielded to perpendicular pressure, causing a fracture on 

 the left side, and flattening the plates at its posterior end, but 

 without materially affecting the original outline of the carapace. 



FAMILY CHELONIID^B. 

 GENUS CHELONE, Owen. 



The bony case of a Sea-turtle is of less weight than those of the 

 preceding order, in adaptation of a natatory life. The upper 

 portion of its irretractile head is covered with bony scales. 



CHELONE PLANICEPS, Oiven., 



This species, which unmistakably shews its marine character, 

 is remarkable for several peculiarities in the shell which distinguish 

 it from all other recent and existing Sea-turtles, and was probably 

 their first representation in geological times. Found in the Portland 

 Sands, Portland. 



CHELONE OBOVATA, Owen. 



Chelone obovata differs from the genuine type in the shape of the 

 carapace, which is broadest at the junction of the fifth and sixth 

 ribs, occasioning an expansion of the marginal plates. Found in 

 the Middle Purbeck-beds, Swanage. 



