WEALDEN CROCODILES. 637 



saurs, Polyptychodonts, and Mosasaurs. The oolitic species of Crocodile (' Crocodile de 

 Caen.'') is signalized by Cuvier as " I'espece la luieu.x cuirassee de tout le genre." 



But the Goniopholis of the Wealden and Purbeck formations surpassed even the 

 Teleosaiirus Cadoiiiensis and its congeners in this part of its organization. 



The great quadrangular dorsal scutes of Gouiop/iolis are distinguished by the presence 

 of a conical obtuse process continued from one of the angles transversely to the long 

 axis of the scute, like the peg or tooth of a tile, which fits into a depression on the under 

 surface of the opposite angle of the adjoining scute, thus serving to bind together the 

 plates of the imbricated bony armour and repeating a structure which is characteristic of 

 the large bony and enamelled scales of many extinct ganoid fishes." The hexagonal 

 ventral scutes of Gonio2jJioIis were firmly joined together by broad sutural borders. No 

 knight of old was encased in jointed mail of better proof than these Crocodiles of an 

 older world. 



But the inimical contemporaries of those Crocodiles have passed away. No repre- 

 sentative of Mosasaurian, Plesiosaurian, or Ichthyosaurian families lived after the secondary 

 epoch. Crocodiles alone of the larger aquatic saurians continued on to the present 

 times more fortunate than their predecessors in respect to possible hostile fellow denizens 

 of the deep. 



Certain it is that the defensive armour of Procoelian Crocodiles has degenerated. 

 Bony ventral scutes are exceptional in them,' and the dorsal ones are fewer, thinner, less 

 closely arranged and less firmly connected with one another. And if this change can be 

 connected with the disappearance of Beptilia against the attacks of which a better coat 

 of mail may have advantaged the contemporary Mesozoic Crocodilia, it may further be 

 remarked that diminution of weight would favour Crocodilian movements in air, and that 

 a loosely-jointed armour would less impede the evolutions required to catch a prey on land. 



In this relation, also, arising out of the introduction in tertiary times of many species 

 of warm-blooded Mammals frequenting the banks of lakes and rivers tenanted by 

 carnivorous Alligators and Crocodiles, I have been led to ponder upon the well-marked 

 difference in the relative position of the ' palatonares ' (internal or posterior nostrils) 

 which exists between the secondary and tertiary Crocodiles. 



The physiologist discerns in the palatal and gular structures concomitant with the back- 

 ward position and small size of the ' palatonares ' in the existing Crocodiles and Alligators 

 of Asia, Africa, and America, the power of holding submerged a powerful Mammiferous 

 (luadruped without the streams of water traversing the great cavity of the mouth during 

 the struggle getting access to the posterior nostrils and windpipe of the amphibious 

 assailant. The valvular mechanism applicable to, or, I may say, possible with, the 



^ Cuv., Teleosaiirus cadomensis, Geoffr. 



2 " Report on British Fossil Reptiles," ' Reports of Biitisli Association,' 8vo, 18-11, p. 70. 



3 Observed by Natterer in certain Saiuh-American Alligators, ' Beitrag fur iiiihareu kenntniss der 

 Siid-Amerikanischeu AUigatoseu Ann. Mus. Wien,' ii (18-10), p. 313. 



