FOSSIL REPTILES OF DORSET. 9 



south-west counties ; those whose vertebrae are concave at both 

 ends, or only concave behind, are extinct. The skull is distinguished 

 from other Keptiles by its osseous palate, including the maxillae 

 palatines and pterygoids expanded into bony plates. The 

 prolongation of the palatines requires a secondary posterior nares, 

 the nasal chambers consequently communicate with the mouth by 

 apertures which are either situated beneath the anterior part of the 

 skull (Professor Huxley's sub-order Parasuchia) as with Stagonolepis 

 and Belodon, both extinct since the upper Triassic age ; or 

 beneath the middle of the skull, as in the sub-order Mesosuchia, 

 represented by Teleosaurus, Metriorhynchus, Goniopholis ? &c. ; 

 or beneath the hinderpart of the skull, as in the sub-order Eusuchia, 

 represented by the highly specialized crocodilian type of Crocodile, 

 Alligator, and Gavial.* 



Modern Crocodiles are furnished with a peculiar apparatus 

 attached to the inside of the mouth, which is of essential import- 

 ance when struggling in the water with their prey. The back-part 

 of the mouth is furnished with a double valvate structure, one 

 fleshy and membranous, the other a gristly plate which rises 

 from the root of the tongue, preventing the water when the 

 mouth is open from entering either the hinder-nostril or the glottis ; 

 the two valves together form a complete barrier to prevent the 

 admission of water when the animal's mouth is open under the 

 surface. It is worthy of notice that, although the jaws of 

 Goniopholis were large enough to grapple with large mammals, 

 there is no evidence of any large mammal's existence anterior to the 

 Tertiary period, Mammals up to that age were of very small size, 

 the largest scarcely exceeding that of a polecat ; no complete cranium 

 has ever been found, neither is there any satisfactory evidence of 

 the vertebral column and limbs of these diminutive Mammals. Of 

 the thirty described species from European strata by far the greater 

 number have been found in the neighbourhood of Swanagef in a 



*Huxley on the Evolution of Crocodilia, Q.J.G.S., vol. xxxi., p. 423, 1875. 

 t See Fossil Mammalia of the Mesozoic Formation, Owen Pal. Soc. Mem., 

 1870. 



