68 



THE TKIAS. 



as being nearer to the Saurian character. This animal was 

 under eighteen feet long, and altogether a feebler creature than 

 the Ichthyosaur, which seems to have made it a prey. Yet it 

 was itself one of the destructive potentates of the early seas. 

 A body, generally fish-like, though framed on vertebrae pre- 

 senting less concave ends, and which terminated in a short 

 tail, serving only as a rudder, was furnished with a long neck 

 and small head, together with four slender paddles, more 

 cetacean than those of the Ichthyosaur. Moving, like that 

 animal, quickly in the water, by means of the special organs 

 designed for the purpose, the Plesiosaur would have a further 

 advantage in its long, flexible, serpent-like neck ; but the small 

 size of the head, though there we find the same superior 

 arrangement of teeth seen in the thecodonts, must have ren- 

 dered it a much less formidable creature than that last de- 

 scribed. Professor Owen regards it as fitted to live near shores 

 and to ascend estuaries. 



The attention of the geologists of the United States has been 

 called to certain footmarks in the sandstone of the valleys of 

 Connecticut (Fig. 32), indicative, as they think, of birds of the 

 orders Grallatores (waders) and Rasores (scrapers). "The 

 footsteps appear in regular succession on the continuous track 



FIG. 44. 



Impressions of Birds' feet on Sandstone. 



