REPTILES ABUNDANT. 59 



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 rendered 

 it a much less formidable creature than that last described. 

 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 sandstones of the 

 valley of Connecticut, indicative, as they think, of birds of 

 the orders Grallatores (waders) and Rasores (scrapers.) 

 " The footsteps appear in regular succession on the continuous 

 track of an animal, in the act of walking or running, with the 

 right and left foot always in their relative places. The dis- 

 tance of the intervals between each footstep on the same track 

 is occasionaHy varied, but to no greater amount than may be ex- 

 plained by the bird having altered its pace. Many tracks of dif- 

 ferent individuals and different species are often found crossing 

 each other, and crowded, like impressions of feet upon the 

 shores of a muddy stream, where ducks and geese resort." ( 34 ) 

 Some of these prints indicate small animals, but others denote 

 birds of what would now be an unusually large size, one having 

 a foot fifteen inches in length, and a stride of from four to six 

 feet. There are anomalies in the forms of some of the feet ; 

 but their being the vestiges of birds has for some years been 

 generally admitted. There is, however, some uncertainty re- 

 garding the date of the rocks which present these memorials, 

 for the phenomena of superposition only denote their being 

 between the carboniferous and cretaceous formations, and an 

 exact place is assigned them, merely upon the strength of the 

 discovery that they present fish of certain genera never found 

 above the Triassic series. Along with distinctly ornithic 

 footmarks are those of the Labyrinthodont. Altogether, above 

 thirty species of Triassic birds are made out from these ves- 

 tiges by American geologists. 



