146 



THE PERMO-CARBONIFEROUS RED BEDS OF 



larger fern-like plants, probably formed its home, from which it descended 

 to fly with lightning speed to some other place of refuge or to seek its food, 

 which very possibly consisted, in part at least, of swift flying or crawling 

 insects which the slower reptiles could not capture. 



Williston estimates the length of Arcoscelis at about 75 to 80 centimeters. 

 Though this is the only known form supposed to have led an arboreal life, 

 we can not doubt that there were many more whose remains we can never 



Fig. 31. — Areoscelis gracilis Williston. About one-seventh natural size. 



hope to find, unless a few of them come to light, preserved by similar acci- 

 dents to those which brought the bodies of a few individuals of the genus 

 Areoscelis into the bone-bed where they were preserved. There was, in all 

 probability, an abundance of terrestrial and arboreal life which will never be 

 revealed to us." 



» Williston has very recently (Jour. Geol., vol. xxii, No. 4, 1914) published a more complete description 

 of Areoscelis, in which he asserts its relationship to the Lacertilia. " I have no hesitation in saying that the 

 skull and skeleton of Areoscelis present distinctly primitive characters of the Squamata, to such an extent 

 that I believe the genus has a definite phylogenetic relationship to the order." 



