126 



THE MIDDLE PAST. 



diminished scale, the line of sauroid fishes that had its 

 culmination in the estuaries of the carboniferous era. But 

 if sauroid fishes are on the wane, true reptiles marine and 

 amphibious are strikingly on the increase, their teeth, bones, 

 and footprints foreshadowing that enormous development 

 and variety that found its meridian during the oolite epoch. 

 Of these the gigantic frog-like labyrinthodon, the plesio- 

 saur, pliytosaur, and thecodo?itosaur, the small lizard-like 

 telerpeton of the Elgin sandstones, the larger liyperodape- 



Telerpeton Eljinense 



don, and the crocodile-like staganolepis of the same for- 

 mation, are perhaps the most noticeable forms ; while 

 innumerable foot-tracks (chelichnm, cheirotherium, batrich- 

 nis, &c.) point partly to turtle -like, partly to frog -like, 

 and partly to crocodilian-like genera. 



Still higher in the scale of life rank the foot- tracks of 

 gigantic birds, and the teeth and jaws of small insectivorous 

 mammals. These fossil foot-prints (ichnites) form one of the 

 most curious features of the period, and their study (iehno- 

 logy) constitutes one of the most interesting chapters in 

 geology.* In the successive stages of the earth's history 



* The valley of the Connecticut in America, Corncockle Muir in Dum- 

 friesshire, Storeton in Cheshire, and Hildberghausen in Germany, have 

 been, as yet, the chief repositories of these fossil footprints. So abundant 

 are they in the Connecticut sandstones, which are mainly triassic (the 

 upper being of the age of the lias, and the lower perhaps permian), that 



