BY C. W. DE VIS. 
1287 
side of its posterior surface ; in this it is in agi’eement with the 
fossil. The ulnar condyle is more shortly ovate and less deeply 
separated from the radial in both species of Plotus, jiast and 
present, than it is in the Pelican. The endocondylar tuhei’cle, 
reduced in Pelecanus to one obtuse ridge, and forming in the living 
Darter a convex cushion-like pi’ominence, is in the fossil species an 
elongately triangular excrescence ; the posterior end of the 
tuberosity on this side, a broad convex surface in the Pelican, is, in 
the recent Plotm and still more in the fossil, produced backwards 
into a sharp compressed plate beyond the articulating surface for 
the ulna. On the inner or anconal side of the head of the fossil 
we miss the very distinct tricipital ridge of Plotus, finding only an 
inferior development of it as in Pelecanus ; but on the other hand 
the ancono-deltoid ridge so conspicuous in the Pelican bone is no 
more recognizable in the fossil than in the recent Darter. Similarly 
the sub-tuberous fossa is, as it is in the Pelican, much more deeply 
excavated than it is in the recent Plotus, and instead of affording 
to the air cells an open cancellated communication with the interior 
of the bone it is merely pierced, as in Plotus, with a few small 
foi-amina. In the distal end on this side the structure and form 
of Plotus are anticipated in every detail. 
Together with the essential traits of Plotus this bone has, as we 
have seen, a few indications of extraneous affinity — perhaps we 
may infer that as an early form of the genus it bad not attained 
the high specialization of its later representative. Several 
differences from P. nova-hollandixe have already been mentioned, 
sufficient perhaps to establish its specific rank j it may be further 
noted, however, that in the extinct bird the pectoral ridge is lowei', 
the distal end le.ss expanded, the curvatures of the shaft much less, 
aiid the size one-thiixl smaller. The palmar impression is alike in 
both. 
Xenokiiynchus nanus, n.sp. 
(Id. x.xxv. figs. 11a, lib). 
Distal half of a right tibia. — An elevation of the palmar end of 
the rotular surface, and a well-defined continuation upon it of the 
rotular channel, are features of the avine tibia which grow 
