CLINTON GROUP. 
33 
Besides the regular continuous trails described, and which 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 sand jr 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 having 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 proving. 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 Kelceno 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 evidence 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 this period ; and even admitting their existence, they were not, probably, furnished with five 
toes or nails ; neither do the tracks appear like impressions 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 
[Palaeontology— Vol. ii.] 5 
