0. C. Marsh—Notice of a new Fossil Mammal. 459 
It is evident, for instance, that from the facts here stated we 
can estimate, photometrically, the intrinsic brightness of the 
corona, since it was undoubtedly this, acting as a back-ground, 
which enabled the planet, though itself involved to a calculable 
extent in atmospheric glare, to be seen before it reached the 
solar limb. 
The observations were interrupted by haze in the afternoon 
and egress was so nearly invisible that the apparent times of 
contact are not worth giving. 
Allegheny Observatory, May 7, 1878. 
Arr. LXVIIL—Fossil Mammal from the Jurassic of the Rocky 
Mountains ; by Professor O. C. MaRsH. 
ONE of the most interesting discoveries made in the Rocky 
Mountain region is the right lower jaw ot a small mammal 
recently received at the Yale College Museum. The specime 
was found in the Atlantosaurus beds of the Upper Jurassic, 
and the associated fossils are mainly Dinosaurs. 
This specimen is in fair preservation, althou sh most of the 
teeth have been broken off in removing it from the rock. The 
as the corresponding molar of Chironecies variegatus Illiger. 
The angle of the jaw is imperfect, but there are indications that 
The principal dimensions of this specimen are as follows: 
Space occupied by seven posterior tebth cc occl. ico 
Depth of jaw below last molar -------- -------- “4 
Transverse diameter ..------- ---- -------+---- 1°8 
Height of crown of penultimate molar... 45+ i 
Transverse diameter ------------- ---------"-- 15 
The present specimen indicates an animal about as large as 
a weasel. It is of special interest, as hitherto no Jurassic 
mammals have been found in this country. 
Yale College, New Haven, May 13, 1878, 
