JONES —TIIA.ILS, TEA.CKS, XSD SURF^CE-Mi^RKINGS. 133 
m ^ m 
^^^^^^ 
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 ^ Emmous). 
from that part of the trail which was made when the water still 
stood over it, and wheu 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 aniuials. 
"Imprints upon tlie 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 di\ision, 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 
dififer very much, in character and 
form, from many which we may find in drying pools after our summer 
showers. 
" Fig. 108 is not very unlike a figure which I gave several years ago 
in my ' Eeport of the Geology of Xew 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 Palls, 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 
of the Southern States. Here the large rivers and their tributaries, 
such as the Oronoko, Dan, and Cape Fear, 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, 
frogs, lizards, rats, and birds, all of which will 
* ' Palreont. New York State/ vol. ii. pi. 13, fig. 2 : similar to those figurtd in Em- 
mons's ' Agiicult. New York,' vol. i. pi. 15, fig. 3, and pi. 16, fig. 3. 
