0. C. Marsh on Cretaceous and Tertiary Birds. 215 
there has been carefully examined for these fossils by several 
paleontologists. The only specimen hitherto detected was ob- 
tained by Dr. F. V. Hayden, several years since, in the later 
Tertiary beds of the Niobrara river. It is the distal extremi 
reserved, and 
appear to exhibit good distinctive characters. The inner arti- 
cular a is partially broken away, but was evidently much 
an the other, and is continued far backward as a very 
sharp ridge. The outer condyle is somewhat flattened below, 
_ and its posterior extension projects = the surface of the 
shaft, although not so far as that of the inner condyle. The 
trochlear space is rather narrow, and has its deepest part inside 
of the median line. It is slightly concave transversely below, 
and deeply so posteriorly. The ecto-condyloid surface is con- 
cave, but has a low tubercle just in front of its central point. 
The supratendinal bridge is very broad, internal, transverse, and 
its.surface is concave vertically. It spans a very narrow, but 
deep, internal canal. The lower outlet is subtriangular in out- 
line, and looks obliquely forward and downward. e su 
rior aperture is broadly oval, and the upper edge of the bridge 
ig continued slightly above it on either side of the ¢ The 
lower opening has its upper, straight margin slightly rounded, 
and its lower edge is formed by a sharp ridge, which separates 1t 
m the nearly flat intercondyloid space. External to this 
aperture is a prominent tubercle, which has its inner edge on 
the median line, and is connected above by a low ridge with the 
outer elongated tubercle for the attachment of the oblique liga- 
A more prominent crest extends obliquely downward, 
and unites it with the external condyle. The inner margin f 
the canal is bounded by a well defined ridge, which, just above 
the bridge, is inflected over the edge. Externally, the margin 
of the short tibial muscle is we 
The principal dimensions of this specimen are as 
3 
Length of portion preserved, - - - ees 
Depth of external condyle, ess 192 
Width of supratendinal bridge, - “ - -* 
Width of upper outlet, 3 : 
