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33 



CLINTON GROUP. 



Besides the regular continuous trails described, and wliich are clearly due to different species 

 of animals creeping or drawing themselves over the surface of a wet sandy beach, or beneath 

 shallow water, there are numerous other markings which do not furnish characters sufficient to 

 entitle them to a notice in the present state of our knowledge of their origin. Many of these 

 may be due to accidental causes, and such as we see in operation upon our recent sandy beaches, 

 and in the shallow bays and estuaries of our coasts, but which can scarcely be described or 

 understood without reference to specimens, or even to the actual recent and fossil localities. 

 There are, however, some peculiar markings often associated with those previously described, 

 and which, from ha\4ng a pretty uniform character, and being extremely numerous and widely 

 extended, are worthy of our attention. These are so clearly and neatly defined as to furnish 

 convincing evidence that they were made by organic bodies, but of what character, we have no 

 very satisfactory means of provmg. I have heretofore been disposed to refer these tracks to 

 crustaceans ; but I learn from my friend Mr. J. D. Dana, that he has examined existing beaches 

 *■ in the southern latitudes, where crustaceans are numerous, and that the tracks they make in 



travelling over the surface are entirely different from the markings in question, and that their 

 mode of progression also gives a different general character in the group of tracks produced. 

 Prof. Agassiz has suggested that they may be the impressions of the horny hooks of the 

 arms of Cephalopoda which have been left upon the beach by the retiring water, and, while all 

 the soft parts perished, these harder portions produced the impressions still preserved in the 



^ stone. The impression in the lithographic slate of Solenhofen, of the arms of Kelann speciosa of 



MuNSTER, with their clasps or hooks, resembles in some degree these impressions ; but they are 

 nevertheless quite different. In the specimens before us, there is no evidence of a central stipe 

 or arm to which these clasps or hooks were attached, nor any eviilence of a body with which 

 the whole was connected. 



Some of the impressions are made by a pointed body like a spine or claw, and they are for 

 the most part sharp, distinct and decided ; and the motion has been made somewhat obliquely, 

 drawing up a slightly elevated ridge of sand behind it. In others the marking is clearly tridactyle; 

 and we are able even to distinguish impressions with the marks of four and five toes or claws. 

 These are likewise so often connected with others showing single impressions, that they all 

 appear to have been made by the same animal. 



The single hook or claw-like impressions might perhaps have been made by crustaceans 

 with sharp, pointed feet ; but we cannot well see how impressions with three, four, and five 

 * small claw-like markings in the same imprint, could have been made by any crustacean. More- 



over when we examine a single series of these, there does not appear to have been as many 

 appendages as are usual in crustaceans. We are not aware of the existence of lizard-like animals 

 at tills period ; and even admitting their existence, they were not, probably, furnished with five 

 toes or nails ; neither do the tracks appear like unpressions made by the foot of an animal like 

 a lizard. Again, on careful scrutiny it does not appear that the palm or foot has been impressed 

 behind the toes, but that In its stead there is a little elevation of sand. There is but one other 

 class, whose existence is known at this period, to which they can be referred, and these are the 



* [Paleontology — Vol. ii.] 5 



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