8 FOSSIL REPTILES OF DORSET. 



last, from the jaws and teeth ; these have distinct sockets, and are 

 anchylosed to the base of the alveolar groove. The crowns of the 

 molars are compressed laterally and are semicircular ; the foremost 

 inclined to be pointed. It occurs in the Feather-bed of the Middle 

 Purbecks, Durleston Bay, Swanage. 



GENUS ECHINODON, Owen. 

 ECHINODON BECKLESII, Owen. 



A much larger Lizard than either of the last two. The tooth-crown 

 is a modification of Macellodon, also of Iguanodon. The serratures 

 are confined to the upper portion of the teeth, which increase in 

 size downwards towards the base, where there are two spear-like 

 points. The teeth in the premaxillary part of the jaw and the two 

 first in the maxillary are not flattened like the rest ; the third is canine 

 both in shape and position. It was carnivorous. From the 

 Feather-bed, Middle Purbecks, Durleston Bay, Swanage. 



Ten genera and twenty-five species of marsupial mammals, from 

 the size of a mole to that of a polecat, were found associated with 

 these Lizards. The majority of the remains consisted of the lower- 

 jaws, and a very few of the upper maxillaries. There has been no 

 instance of the recovery of an entire skeleton nor of several bones 

 in juxtaposition to each other ; to account for this Dr. Buckland 

 suggested the possibility that the corpses of drowned animals, 

 distended by gases during putrefaction, while floating in the water 

 would lose their hanging lower-jaws, while the rest of the body 

 would drift into the sea. 



ORDER CROCODILIA, Owen. 



This Order differs from Lacertilia in the teeth having distinct 

 sockets, in the venous and arterial blood uniting just outside the heart 

 instead of in it as with other reptiles, by the fixed attachment of 

 the quadrate bone to the skull, and in having an interclavicle and 

 no clavicles. The living representatives, which include Crocodiles, 

 Alligators, and Ga vials, have their vertebrae concave in front ; they 

 appear for the first time in England in the Eocene rocks of the 



