BLACK FLIES. 123 
of low hills, giving us, at every few moments, beautiful 
changes of scenery, and at sunset encamped upon a small 
fork of the Trinity. 
To-day, our oxen suffered terribly from the attacks of large 
black flies, which came in myriads, 
They were as large as humble. bees, and very voracious ; 
their probosces inflicting wounds deep enough to keep the 
blood flowing after the insects fell off from repletion. 
We felt very anxious about our stock, as these flies, with 
searcity of water, which we expected to encounter, would tell 
most fearfully upon them, but = as we rose higher, to 
get rid of them. 
July 18th.—Our course to-day was West, towards the head 
waters of the Little Witchita, passing through fine ranges of 
bluffs, affording many fine views, but the country so broken 
that the working party were constantly employed bridging 
creeks, ravines and branches. 
We passed through the crater of an old voleano, which 
must have been in activity before the flood, from surrounding 
indications, the ground being covered with scorix, among 
which were found fossils. 
The Major shot a prairie snake, a species of adder, about 
eleven feet long, and a rattlesnake, a most formidable reptile, 
fall seven feet long, with teeth an eighth of an inch in length, 
and eleven rattles. Both these specimens were prepared for 
. our collection, ; 
Happening to remark that I thought it fortunate rattle- 
