THE GEOLOGICAL EECORD 223 



no complete skeleton has been jet discovered. The allied 

 Megalosaurus was found by Dr. Bnckland in the Weahh'ii 

 beds in such abundance that he was able to piece together 

 enough of the skeleton to show its affinity to the Iguanodon. 



Order — Sauropterygia 



We now come to the group of aquatic lizards wdiich abounded 

 in all the seas of the Mesozoic period from the Trias to the 

 Chalk. They had lizard-like heads, powerful teeth, both fore 

 and hind limbs converted into paddles, and often with a dilated 

 swimming tail. They varied much in size, but were often 

 very large. Plesiosaurus cramptoni, from the Upper Lias of 

 Whitby, w^as 22 feet long, but some species from the Chalk 

 formation were from 30 to 40 feet long. A skull and jaws 

 of P. grandis, from the Kimmeridge clay, is 6 feet long, which, 

 if the proportions were the same as those of the species here 

 represented (Fig. 60), w-ould have belonged to an animal nearly 

 50 feet long. The whole group w^as extremely varied in form 

 and structure, but all w^ere adapted for preying upon such 

 aquatic or marsh-frequenting animals as abounded during the 

 same period. 



Order — Ichthyopterygia 



All the members of the preceding order have the paddles 

 supported by a complete bony foot or hand composed of five 

 separate fingers and connecting wrist-bones. But in the pres- 

 ent order the adaptation to marine life is more perfect, a dorsal 

 fin and bi-forked tail having been developed (Fig. 61), while 

 the bony skeleton of the four limbs often consists of seven or 

 eight rows of polygonal bones closely fitted together as shown 

 in the drawings here reproduced (Fig. 62 A, B). They were 

 also remarkable for their verv larG:e and hiffhlv oro-anised eves, 

 which, with the lengthened jaws and closely set sharp teeth, indi- 

 cate a perfect adaptation for capturing the fishes which the seas 

 of that age no doubt produced iu the same abundance and almost 

 as great variety as our own. These creatures also varied uiuch 



