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CLINTON GROTJi'. 35 



Itierti should have been numerous, but only that the conditions should have been favorable for 

 their preservation. Therefore in looking at these and the other trails, vre are not to regard the 

 paucity or abundance of any particular class in order to account for their having been made. 

 Throughout all the other strata, there are probably few situations vs'here the conditions have 

 been such as to preserve similar markings if made. It required not only the yielding material, 

 but that it should be so exposed as to become partially hardened previous to the deposition of 

 another layer upon it. We have in this group all these conditions; and therefore such markings 

 as, under other conditions, w^ould have been obliterated, are here preserved^ 



PLATE XV. Figs. 1, 2, 3, 4, 5, B. ^ 



Several of the tracks represented upon this plate are distinctly tridactyle, or even present 

 four and five distinct radiating impressions as of toes or claws. The sand seems, not as if pressed 

 ,by a footj but as if drawn backwards, and the impression thus produced leaves a small elevation 

 or knob of sand behind it. Others present only a simple pit with an elevated point of stone 

 behind, leaving no marks like toes. 



Fig. 1. The small fragment of stone figured presents a surface marked by about six distinct 

 tracks, each one showing the radiating impressions like toes very clearly. Parallel to these are 

 three deep single tracks, having no marks of toes. Almost in the same line is a row of shallow 

 oblique cuts, also without marks of toes, but which unfortunately are not represented in the 

 figure; The exact parallelism of the two ranges, though of different character, induces a belief 

 that they were made by the same animal. The range of tracks at the right hand, which escaped 

 the observation of the artist in the figure, may have been partially obliterated after being made, 

 as they now lie in a kind of depression or channel in which water flowed ; while those on the 

 left hand, preserving the impression of toes, are on a slightly more elevated surface. 



The same specimen is marked in other parts by tracks less distinct than those given, but 

 nevertheless clearly due to impressions made in the soft sand. 



Fig. 2. This figure is from a specimen marked by parallel ranges of tracks, which are more 

 or less distinctly preserved throughout. A row of tracks on the left hand is preserved nearly 

 entire, with the marks of toes or appendages in almost every one. The righthand range is less 

 perfectly preserved, but still distinctly marked^ Towards the lower side are some deep sharp 

 pits, as if made by a single spine or claw. Near the base of the figure are three or four ranges 

 of tracks, crossing the others obliquely. These tracks are slightly different in their character 

 from the others, but still appearing as if made by sharp spines or claws impressed into the mud 

 and withdrawn, leaving sharply elevated ridges on both sides. 



Near the centre of the specimen, the tracks are partially obliterated by another range of 

 shallow pits or tracks made in a double parallel series. 



Fig. 3, is a part of a specimen which shows a double parallel series of tracks, all of which 

 are marked by toe-like appendages, and appear as if made by two animals traveUing in parallel 

 lines. 



