238 L YELL'S ELEMENTS OF GEOLOGY. 



Fossil Footsteps. 



Fig. 235. 



Ammonites nodosus. Muschelkalk. 



a. Side view. b. Front view. 



c. Partially denticulated outline of the septa dividing the chambers. 



Fig. 236. 



Fig. 237. 



Posidonomya 

 ininuta, Bronn. 



a. dvicula socialis. b. Side view of same. 



Characteristic of the Muschelkalk. 



than five genera of large extinct reptiles, all peculiar to the 

 Muschelkalk, as Phytosaurus, Dracosaurus, and others. Upon 

 the whole, Professor Bronn has enumerated, in his LethaBa 

 Geognestica, no less than forty-seven genera of fossil remains 

 from the three divisions of the " Upper New Red" system in 

 Germany ; and these fossils are the more important as being all 

 distinct in species, and many of them in genera, from those of 

 the incumbent Lias or more ancient Magnesian limestone. 



In the Bunter Sandstein near Hildburghausen, some remark- 

 able fossil footsteps have lately been 

 discovered in quarries of a gray quart- 

 zose sandstone. On the upper surfaces 

 of the slabs of stone the steps form de- 

 pressions, while those on the lower sur- 

 faces are in relief. These last are 

 natural casts formed in the subjacent 

 footsteps, as in moulds. The larger 

 prints seem to be those of the hind foot, 

 and are about eight inches long and five 

 wide. Near to each, and at the regular 

 distance of an inch and a half before 

 is a smaller print of a fore-foot 



Fig. 238. 



Single footstep of Chirotherium. CUStan 

 one eighth of nat. size. them 



