The President's Address. By Dr. H. Woodward. 143 



the extraordinary dorsal fin supported upon bony prolongations 

 from the dorsal spines oi' the backbone ; the body is Crocodilian in 

 aspect; the legs were short, the jaws armed with exceedingly 

 sharply pointed teeth, and may have served for the purpose of 

 preying upon fish and other aquatic animals. 



Passing over a number of forms, Dicynodontia, etc., with 

 variously modified teeth and skulls, we come to the division 

 Thekiodontia, remarkable for the resemblance of the skull to that 

 of a carnivorous mammal {Galesaurus, JElurosaurus), and the differ- 

 entiation of the marginal teeth (so far as shape is concerned) into 

 incisors, canines and molars. Only one occipital condyle, how- 

 ever, articulates the skull to the vertebral column. So far as we 

 are able to judge by a knowledge of recent reptiles, they exhibit an 

 advance upon the Amphibia, not only in being provided with a 

 foetal envelope, known as the amnion, but also by breathing by 

 lungs throughout life, and never possessing branchia at any stage. 

 The remarkable form Tritylodon, originally considered by Owen to 

 be a mammal, has now been referred to the Theriodontia. In 

 nearly all these forms the pineal foramen can be distinctly seen ; 

 they have also anterior nares. 



The Saukopterygia {Plesiosauria) form another primitive group 

 of reptiles, in which the bones of the skull in the temporal region 

 contract into a single broad zygomatic arch. Commencing with 

 small amplnbious animals in the Trias, they are represented by 

 larger, truly aquatic forms through the whole of the Secondary period. 

 Although these larger forms (the Plesiosauria). lived wholly in the 

 open sea, they retained their two pairs of pentadactyle limbs, and 

 their long-neck and lizard-like form, in contradistinction to the 

 Ichthyopterygia, which have an extremely shortened neck, and are 

 quite fish-like in external shape. They have a pineal foramen, and 

 exhibit two large supra-temporal vacuities on the skull ; the conical 

 teeth form a single series on the margin of the jaws, and they have 

 distinct sockets. 



In the small Triassic form Lariosaurus, which preceded them, 

 and was probably ancestrally connected, the limbs are elongated and 

 slender, with five digits, and the normal number of phalanges. In 

 the later genera they are modified as paddles, with shortened fore- 

 and hind-limb, but still with only five digits present ; but these 

 are lengthened by the addition of supernumerary phalanges, and are 

 destitute of claws. They have a system of well-developed ventral 

 ribs, and the skin appears to have been destitute of armour. 



The Chelonia may possibly have been developed from a highly 

 modified form of Plesiosaurian. The earliest known Chelonian is 

 met with in the Trias, and differs in no very important degree from 

 the later forms. They have a very wide geological and geographical 

 range. The genus Testudo, which is represented by many large 

 living species, is found fossil in the Siwalik Hills of India and in 



