280 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1918. 



That Dimetrodon was a carnivorous animal is clearly indicated by 

 the powerful incisor and maxillary teeth which are admirably 

 adapted for seizing and holding an active struggling prey. It is not 

 probable that with his short bowed legs and heavy body he was ever 

 capable of running fast or for long distances, but was certainly able 

 to move swiftly for a short space, and thus from where he lay hid- 

 den in the vegetation made short, scuttling rushes upon his prey, end- 

 ing possibly with a short pounce which permitted his weight to add 

 something to the vigor of the attack by tooth and claw. 



The edges of pools were probably the regions most densely popu- 

 lated by the varied amphibian and reptilian forms of the Permian 

 period, and no doubt such places were favorite haunts of the Dime- 

 trodon. 



The National Museum skeleton has a length of about 7 feet, and 

 from the base to the top of the highest spine measures 5 feet 6 inches, 

 and while this is the largest species of its kind single individuals 

 probably reached greater dimensions. 



In plate 6 is shown a photograph of the restoration of Diinetrodon 

 gigas based on the mounted skeleton and which shows the latest con- 

 ception of the probable life appearance of this creature. 



