L. D. Burling — ProtiGhnites and Climactichnites. 389 



side leg tracks ; [g] in one trail the median groove is only 

 impressed at intervals, but these are regular and occur 26 times 

 in a horizontal distance equal to 25 times the width between 

 the tracks ; (A) where the trail crosses a ripple marked surface 

 all traces of ripple mark are obliterated for a distance a little 

 wider than the extreme width of the trail, and the feet tracks 

 are large and coarse with the median groove deeplj' incised ; 

 (^) on a surface adjacent to that showing g occurs a trail simu- 

 lating Protichnites, but without the median groove and with 

 the feet tracks small and sharply impressed ; {j) the side rows 

 of leg tracks are not arranged along a single straight line, but 

 appear to be more or less double ; {k) where the median groove 

 is deep the side tracks are proportionately deep ; {I) where the 

 median groove is only marked at intervals, as in ^, the impres- 

 sions of the legs betray a tendency to be arranged in slightly 

 curved lines concave toward the center, with the crests about 

 as far apart as the intervals dividing the impressions of the 

 median groove and more or less opposite to these impressions ; 

 (m) the number of leg impressions w^as counted in two places 

 on the trail mentioned in ^ ; in one where a group of 9 median 

 groove impressions was available 65 leg impressions occnrred on 

 one side, 63 on the other; in another group of 6 the number 

 of leg impressions was respectively 38 and 40 ; each of these 

 groups was crossed by another trail, and the number of legs 

 may be greater on this account. 



Inferences : (a) Some of the appendages used by the animal 

 in walking were three-toed ; {h) the animal toed in, and toeing 

 in is usually characteristic of heavy low-lying bodies whose 

 feet touch the ground well toward if not beyond the sides of 

 the body ; (g) if the inference in h is correct, the animal was 

 neither wider nor narrower than the track and individuals 

 ranged in size from 2 to 6 inches in width ; (d) its body was 

 either extremely flexible or else short and more or less circular 

 in outline ; {e) the animal usually (see i) did not carry the 

 entire weight of its body on its legs, but allowed a median por- 

 tion to rest on the bottom and this portion was apparently 

 forked in some, club-shaped in others — perhaps a sexual differ- 

 ence ; if) the part of the body which rested on the bottom was 

 not the telson of a Zi^mdus-like crustacean or trilobite, but 

 was a process situated somewhere between or very close to the 

 legs ; (g) the animal w^as able to bear almost its whole weight 

 (all, if i was made by the same animal) on its legs, but where 

 its median portion did just graze the ground it did so once for 

 every time it moved forward through a distance equal to its 

 own w^idth ; this corroborates d in indicating the general cor- 

 rectness of making the animal round or oval in outline ; (A) 

 the animal was heavy, and its legs were comparatively short 



