1286 A GLLMPSE OF THE POST-TERTIARY AVIFAUNA OF QUEENSLAND, 
tubercle more obtuse ; the precondylar impression smaller but 
deeper, and separated from the articular surface by a deeper 
cavity between the ectocondylar tubercle and the radial condyle. 
The sum of these differences forbidding the identification of the 
existing coot with its feebler ancestor, it becomes necessary to 
distinguish the latter by name, and the colourless one, i^rior, is 
suggested for it. 
Plotus parvus, n.sp. 
(PI. XXXV. figs. 10a, 10b.) 
Left humerus. — There is no difficulty in recognising the arm bone 
of a Darter. Having its share of the characteristics of the bone 
in the Pelecanidae, it has also peculiarities sufficiently well marked 
for comparative tests. The jjectoral crest is short and low, and 
from it the edge of the bone runs with a straight course to the 
radial tuberosity ; this in Pelecanus is a low rounded prominence, 
but in Plotus and in the fossil is obliquely truncated anteriorly, 
and there presents a nearly flat triangular suiface ; on the palmar 
surface of the radial side of the head is a conspicuous impression 
— broad and shallow in Pelecanus, more contracted and deejier in 
Plotus. Round the anterior edge of this depression there is in the 
Pelican of Australia a curved row of equal-sized and equidistant 
foramina ; in the Darter the foramina are reduced and inconstant 
in number, and the one at the ulnar end of the .series is by much 
the largest. The extinct form shows in this respect more affinity 
with the Pelican than with the recent Darter, its foramina being 
numerous and regular, but minute. The .sub-tuberous ridge, 
bettering its name in Pelecanus, hai-dly deserves it in either the 
extinct or living species of Plotus] in both it is a compressed plate : 
but on the other hand the ulnar tuberosity produced and over- 
hanging the scapular groove in Plotus, presents in the extinct bird 
a forecast of the low trihedral form of it in Pelecanus. At the distal 
end the radial condyle is elongate, oblique, with a strong sigmoid 
curve in Pelecanus, and is widely separate from the ectocondylar 
tubercle ; in the separation is by a narrow gi'oove only, and, 
reversing the condition in Pelecinus, the condyle itself presents 
more articulating surface on the inner than on the outer 
