20 
PROCEEDINGS OF THE ACADEMY 01* 
themselves at the ends of the line, and watched for meteors, carefully noting the 
times of their appearance, and their couraes. By these means, the observers 
were enabled to identify twenty- two of these objects ; and the data thus derived, 
yielded satisfactory results as to height and velocity. 
The most remarkable feature of their observations, was, that one of the meteors 
instead of falling, moved in a direction aioay from the earth. 
A curv^e in the train of a meteor with the convexity downward, would indi- 
cate a motion from the earth. 
Nearly all the phenomena of meteors have been accounted for by theories 
which men of science regard, if not as satisfactory, at least as plausible ; but I 
believc/no astronomer has yet had the hardihood to attempt to explain, how a 
meteor can approach near enough to our planet to be inflamed by its atmosphere, 
and become visible to its inhabitants, and then move off in defiance of the law 
of gravitation. 
I have detailed experiments which show that stationary objects in the heavens, 
under certain circumstances, appear associated with flashes of light which are 
curved with their convexity towards the earth ; and I trust that what I have 
said will convince the Academy that there is the greatest probability that the 
anomalous appearance described by Messrs. Brandes and Benzenberg, was only 
an example of the optical illusion which it is the purpose of this paper to explain. 
Notice of Remains of Extinct Vertebrata, from the Valley of the Niobrara River, 
collected during the Exploring Expedition of 1867, in Nebraska, under the 
command of Lieut. G. K. Warren, TJ. S. Top. Eng., by Dr. F. V. Hayden, Geolo- 
gist to the Expedition.* 
BY JOSEPH LEIDY, M. D. 
During the Exploring Expedition of the last year in Nebraska, under the 
command of Lieut. Gl. K. Warren, the Greologist of the Expedition, Dr. F. V. 
Hayden collected a number of remains of mammals and turtles, from a deposit, 
in the valley of the Niobrara River (Swift-running-water ; L'eau-qui-court), 
which he suspects to be of pliocene age. The collection is an exceedingly in- 
teresting and important one ; and the anatomical characters of the specimens 
support the opinion of their discoverer, that the formation, from which they 
were obtained, belongs to the later tertiary period. 
The extinct fauna of the Niobrara is especially rich in remains of ruminating 
and equine animals. Among the former are several peculiar genera, of which 
two are closely allied to Oreodon and Leptauchenia, of the miocene deposit of 
the Mauvaises Terres : one is allied to the Musk-deer, and another closely ap- 
proaches the Camel. Besides the remains of a true species of Equus, the col- 
^Washington, (D. C.) March 8, 1858. 
Capt. A. A. Humphreys, T. E., Ch'ge OS. Expl. and Surveys. 
Sm : Professor Joseph Leidy has prepared a ' ' Notice of Remains of Extinct 
Vertebrates," constituting twenty-eight new species, collected by Dr. Hayden 
along the Niobrara River, on the Expedition placed under my command by the 
War Department, during the past summer, which, it is desirable, should be 
published at once in the Proceedings of the Academy of Natural Sciences of 
Philadelphia. The permission of the Honorable Secretary of War, to make the 
piiblication, is requested. 
Very, respectfully, sir, your obedient servant, 
G. K. Warren, 
Lieut. Top. Eng'rs. 
Submitted to the Secretary of War. The publication is approved by him. 
A. A. Humphreys, 
Capt. Top. Eng'rs. in Charge. 
[March, 
