G54 S. W. WILLISTON 



tion in the American genus Clepsydrops. These two specimens 

 of Haptodus add nothing to our knowledge of Paleohatteria, if 

 they be the same, except that one is a half larger than those 

 studied by Credner. 



Kadaliosaurus priscus Credner. This genus, so far as I am 

 aware, is represented by a single known specimen, from the mid- 

 dle Rothliegende of Germany, described and figured by Credner. 

 The specimen, unfortunately, lacks the skull, the pectoral girdle 

 and most of the tail, and has only stray bones of the feet. So 

 far as it goes, as described and figured by Credner, it has a 

 remarkable resemblance to Araeoscelis Williston, from the Clear 

 Fork beds of Texas. It differs apparently in the possession of 

 a well defined ventral armor, of which there is little or no evi- 

 dence in Araeoscelis; perhaps also in having a short tail, though 

 I should think it more probable that the tail is long, as in Arae- 

 oscelis. The vertebral spines in both are very short, the centra 

 are notochordal, and the body is very slender. The resemblance 

 of the limb bones in the two genera is astonishing; so great 

 indeed that Credner's figures would serve equally well for Arae- 

 oscelis. Not only are the front and hind limbs of equal length, 

 but the epipodials are as long as the propodials, and all are very 

 slender. The femora of both forms are identical in their slen- 

 derness and sigmoid curvature. What is still more remarkable, 

 the humeri, apparently agreeing quite in shape, have both entepi- 

 condylar and ectepicondylar foramina, a character unknown in 

 any other reptile of lower Permian age. There is no puboischiadic 

 vacuity in the pelvis of either genus. It would seem impossible 

 that such extraordinary resemblances should be solely the result 

 of convergent evolution. I believe that they are related and 

 that both should be placed, for the present at least, in the same 

 family. The family differs so much from others of the Permo- 

 carboniferous that its relationships may well remain a matter of 

 doubt. Araeoscelis has a single temporal vacuity of large size, 

 and was a very slender, and slender legged, long tailed lizard-like 

 reptile, almost certainly of climbing habits; its toes have acumi- 

 nate claws. 



