LABI DOS AURUS COPE 321 



conjecture as to how and where the creatures lived. The two 

 striking characters seen in the skeleton are the elongated, hook- 

 like incisor teeth and the very powerful feet. Were they corre- 

 lated ? I believe that they were. There is no evidence that the 

 powerful feet were developed for use in swimming, though doubt- 

 less the creatures swam well. Nor is there any evidence that the 

 creatures used them for digging holes in which to crawl, for the 

 very good reason that the front legs were altogether too short; 

 they could not have scratched their own noses, much less dig 

 holes for the body to enter. Why not then assume that the feet 

 were developed for digging for food ? The epipodials are relatively 

 short, a character constantly found in animals using their legs for 

 propulsion in the water. But why not the same shortening to give 

 greater immediate power in digging? I believe, then, that 

 Labidosaurus lived about the lowlands, on the borders of the seas 

 or lakes, and found its livelihood in extricating worms and larvae 

 from the rocks or soil, for which the long, hooklike front teeth were 

 admirably fitted. The posterior teeth in Labidosaurus were not 

 strictly carnivorous; they were better adapted for cutting than for 

 tearing or seizing. They are flattened, with an obtusely pointed 

 apex; and the palatine teeth were very small, except those of the 

 "transpalatine" part of the pterygoids. The motion of the head 

 upon the shoulders was limited laterally, rather free vertically. 

 The trunk was not very flexible. The spines were short, but the 

 great development of the arches of the vertebrae furnished ample 

 place for the attachment of muscles controlling the head. Finally, 

 in motion the animal must have been slow and sluggish. 



In some respects Labidosaurus is the most specialized of all 

 the American cotylosaurs, especially in the loss of the supra- 

 temporal and tabular bones, rarely absent in other cotylosaurs; 

 and in the reduction of the dermosupraoccipitals, and their restric- 

 tion to the occipital surface of the skull. The genus could not have 

 been ancestral to any known later cotylosaurs, though possibly 

 the Captorhinidae may have been allied to the ancestral stock of 

 the Procolophonia of the Trias. 



