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THE AMERICAN NATURALIST [Vol. XLIV 



like microsaurian, Amphibamus yrandiceps, from the 

 Mazon Creek shales of Illinois. The writer has been for- 

 tunate in observing the outline of the body of this 

 species. He has also observed muscle fibers in the ab- 

 dominal wall and the outline of the body in 'i ml it amis 

 walcotti from the Coal Measures of Ohio. He has de- 

 scribed, also, the fin membranes, the lateral line organs, 

 the form of the body and the "pigmentum nigrum" of 

 the eye of Mi< rcrpetoii caudatum from the Mazon Creek 

 shales. Dollo has described an unusual amphibian from 

 the Wealden of Bernissart, Belgium, 11 plaobatrachus 

 cropii, which showed the preservation of some of the 

 body membranes and thus a portion of the form of the 

 body. Numerous observers have written on the form of 

 the feet in amphibia as they have been recorded by their 

 footprints in the rocks. 



Nothing has ever been contributed to the structure of 

 the intestinal tract of the fossil amphibia, and from the 

 nature of the case as well as from the extreme rarity of 

 approximately complete specimens of these animals it 

 would be an unexpected event if such were discovered. 

 Our confidence in the preserving powers of the rocks 

 grows, however, from year to year, and if we look long 

 enough we can not fail to uncover many things of in- 

 terest. 



The amphibia of the Mazon Creek shales have always 

 been noted for the unusual perfection of their preserva- 

 tion, which they have shared with other animals and with 

 the plants from that historic locality. Amphibamus 

 grandiceps, the first amphibian described from these 

 shales, was made known in 1865 by Professor Cope from 

 an almost perfect specimen. The next species made 

 known from these shales was the form described in 1909 

 by the writer under the name Micrerpeton caudatum. 



somewhat surprising, on that account, to observe among 



