684 GEOLOGICAL SURVEY OF THE TERRITORIES. 
Now, it depends how far this ligament is conducted backwards as to 
how many of the anterior sacral vertebre bear hypapophyses, as from 
its attachment to the hypapophysis (we have never seen it commence 
on the cervicals, though the directions assumed by their processes bear 
it out) of the first dorsal it completes a long shallow are of an ellipse, 
in which the lower margins of the hypapophyses are found and assist 
to complete. This semi-osseous, Semi-membranous, attenuated median 
plate dips down into the thoracic cavity in the living bird for some little 
distance, as an interpneumonic septum. 
The number of free caudal vertebre in the adult Sage Cock is five, 
Pediacetes phasianellus. 
and to these is to be added the pygostyle. They all have pretty much 
the same general appearance, differing principally in the length of their 
outstanding transverse processes. In this respect the first and second 
are about equal; in the third and fourth two or three millimetres are 
added on either side, with a roughened tuberosity above; while the fifth 
and last is in appearance and size very much ‘like the first. These dia- 
pophyses are rounded at their extremities, and all slightly deflected. 
The centra are transversely elliptical and of good size. The neura- 
pophyses arise from them to inclose a subcireular neural canal, which is 
roofed over by the bifid and clubbed terminations of the elements, that 
hook or lean forward (Plate IX, Fig. 66; Plate XIII, Fig. 91). We 
have never observed an hypapophsis upon any of them; and all the 
elements and processes, as always occurs in the cocygeal series, are 
more or less imperfectly developed. 
The pygostyle is an acute subcompressed triangle with tuberous base. 
Anteriorly and above it exhibts a bifurcated process that simulates the 
crests of the series; below this a shallow facet, for articulation with the 
last caudal, and a feeble subconical depression to protect the termina- 
tion of the myelon between the two. Behind it has, at its lower angle, 
a deep groove, with a heavy bony rim or margin that shows a constric- 
_ tion near its middle (Plate IX, Fig. 65). This formation is easily ex- 
plained when we come to examine the development of this compound 
appendage in the chick of a day or so old. This will reveal the fact 
