J0:N"ES — TEA.TL3, TRICKS, AT^D SURE AC E-MARKINGS. 



133 



an apodous larva. This imprint (fig*. 

 107) was made upon an impressible 

 surface, but sufficiently indurated to 

 preserve the form and character of the 

 trail. This trail, however, is gradually 

 changed into one having the form ex- 

 hibited in fig. 108 (fig. 6). This fact is 

 important, and should be remembered. 

 The change in this instance is due to 

 the change in the consistence of the 

 mud itself. In the last figure it is copied ^ Emmons), 



from that part of the trail which was made when the water still 

 stood over it, and when it was so liquid as to flow and fill up, in part, 

 the imprint. The two patterns are so different that, if they were apart, 

 they would very naturally be attributed to two quite different animals. 



"Imprints upon the Taconic slates 

 in Maine and New York do not dif- 

 fer materially from the foregoing. 

 So, also, those upon shales belong- 

 ing to the Ontario division, near 

 Utica, which I was the first to point 

 out, and which are figured in Mr. 

 Hall's second volume of Palaeonto- 

 logy,* appear to have been made by 

 water-insects ; at least, they do not 

 differ very much, in character and 

 form, from many which we may find in drying pools after our summer 

 showers. 



" Eig. 108 is not very unlike a figure which I gave several years ago 

 in my ' Report of the Geology of New York,' and which were made 

 upon the green slates belonging to the Taconic system in Maine, 

 and slates, too, which are among the oldest sediments in the world. 



" If the foregoing remarks and observations are true, it proves that 

 the soft fragile larvse of insects existed in the earliest periods, or at 

 the time when the oldest sediments were deposited." 



Going on to speak of the fossil tracks and trails in the Connecticut 

 sandstones at Turner's Ealls, Professor Emmons expresses a belief 

 that the tracked surfaces formed a border around and outside the 

 main body of the sediment, and were due to the overflow of rivers 

 and ponds after heavy rain-falls. " This view of the subject," he says, 

 " is sustained by what takes place in every great freshet in the rivers 

 ot the Southern States. Here the large rivers and their tributaries, 

 such as the Oronoko, Dan, and Cape Eear, overflow their banks, and 

 spread over the meadows or low ground, upon which a sediment two 

 or three inches thick is thrown down. The river, on subsiding, leaves 

 the deposit to dry gradually ; and, in the meantime, it will be tracked 

 by insects, worms, frogs, lizards, rats, and birds, all of which will 



* ' Palseont. New York State/ vol. ii. pi. 13, tig. 2 : similar to those figured in Em- 

 mons's ' Agricult.New York,' vol. i. pi. 15, fig. 3, and pi. 16, fig. 3. 



. 6 (108, Eiuraous). 



