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THE AMERICAN NATURALIST [Vol. XLVIII 



and in the genera of the chameleons in which the same 

 thing occurs, for example, Chameleo cristatus Stutch., the 

 spines are united into a thin dorsal crest by the integu- 

 ment and are further united by a thin membrane carry- 

 ing scattered muscle fibers. The outline of the dorsal 

 fin shown in the restoration is suggested by all the speci- 

 mens in which the spines have been preserved. The sharp 

 recurvature of the spines in the lumbar region is less 

 pronounced in the specimen from which the restoration 

 was drawn than in some other and it is possible that in 

 other species there was even more of an overhang of the 

 posterior end. The spines are abruptly shortened in the 

 pelvic region and rapidly decrease on the tail. The length 

 of the tail is not known but in all probability was elongate 

 rather than short and stumpy. 



The limbs were short and heavy with the forearm and 

 foreleg shorter than the proximal segment of the limb, a 

 condition which is quite common in slow moving forms or 

 those of aquatic or palustrial habit, and just the reverse 

 of the condition found in the active, raptorial Dimetro- 

 don, The bones of the feet have not been found in posi- 

 tion, but in the great Brier Creek Bone-bed in Archer 

 County, Texas, excavated by an expedition from the Uni- 

 versity of Michigan in the summer of 1913, numerous 

 large foot bones of a character different from those of 

 Dimetrodon or the cotylosaur Diadectes were found as- 

 sociated with the spines of Edaphosaurus and with large 

 claws. It is believed that the foot of that animal was of 

 goodly size and armed with sharp claws well fitted for 

 digging in the soft earth or vegetation, tearing open rot- 

 ten logs and overturning rocks in search of food. 



It has been noted by all collectors in the Texas beds that 

 isolated vertebrae of Edaphosaurus are among the most 

 common fossils found but that any portion of an asso- 

 ciated skeleton is extremely rare. This has led to the 

 suggestion that the remains of the animals were trans- 

 ported for some distance after death, probably by rivers 

 from a higher land. 



