762 GEOLOGICAL SURVEY OF THE TERRITORIES. 
the cuts, a, a is an outline sketch of the pygostyle from Sarcorhamphus 
gryphus ; it shows very well, and is, in fact, typical of the parallelo- 
gramic form this bone assumes in the Cathartide; b and Db‘ is the lat- 
eral and posterior view of the bone from Gyparchus papa ; in this Vulture 
we observe that the upper portion of the bone, ur rather the upper and 
posterior angle, is very much thickened. 
Cathartes aura, shown in ¢ and c’, still retains the usual outline of the 
other Vultures of this family, while in Catharista atrata, d and d’, the 
lower and outer angle is rounded off, but the common form is still very 
decidedly retained in its upper half. In Neophron percnopterus, seen in e€ 
and e’, we discover a marked leaning towards the form of the bone as 
it is known to us among the majority of the Falconide. 
Eccentricity of form stamps nearly every part of the bony frame- 
work of the African Secretary Bird, Gypogeranus, so we are not so much 
surprised to find the shape the coccygeal vomer takes on, a shape 
that we present in f and f’. That the diapophyses of the anterior 
vertebra that assisted in making this bone have been retained with 
great prominence is very evident to us, and they are shown both from 
lateral and posterior aspects. The size of the usual foramen still fur- 
ther individualizes this vertebra. 
Approximate outlines of the bone for Otogyps calvus (g) and Vultur 
cinerea (g') are next in order given, and we note that in the first the 
tendency is devidedly to partake of Falco-form type of the segment, 
while just the reverse is seen in the second, where it assumes a shape 
quite like the Cathartide. 
The two more common patterns, as seen among the vast majority of 
Hawks, Owls, and Eagles, we find sharply portrayed in Circus hudsonius 
(k, k’), and in Polyborus tharus (l, l’). On the other hand, we give nota- 
ble exceptions to this triangular style in Tinnunculus sparverius (h and 
lh’), Accipiter coopert (i and 2), and in Micrastur brachypterus (7 and jj‘). 
So we see that among these Vultures, as well as the Falconide, the 
form that the pygostyle takes on can only be utilized as a distinctive 
matk in the question of differential diagnosis, when taken in connection 
with other groups of characters found either in the bird’s external 
topography or its internal structure. 
The number of the dorso-vertebral ribs in any of the Cathartide can 
easily be ascertained by consulting the table of vertebre (the second 
accompanying this monograph), as, of course, every dorsal vertebra has 
its pair of free dorsal ribs, these being articulated in the usual manner 
with the sternum, by the intervention of the sternal ribs. The ribs as 
found among the American Vultures are very robust and strong bones, 
representing, as they do, fit accompaniments of a skeleton notorious 
for its general massiveness. As is most usual in the class Aves, the 
neck bearing the capitulum of the rib at its extremity lengthens as we 
pass backwards towards the pelvic end of the body, in due proportion 
does the one bearing the tuberculum shorten, until in the latter we have 
the transverse process of the vertebra, in the last dorsal resting for the 
outer third of its length against the true neck of the rib apposed to it, 
and the tubercular pedicle has become sessile with the body. 
The ribs of the Cathartida, or such of them as are found in the dorsal. 
division of the column, are very broad throughout their entire lengths, 
the broadest part being found at their superior thirds; this transverse 
compression gives rise.to sharp anterior and posterior borders, and long 
elliptical facets, placed longitudinally below for the sternal ribs. 
All of the dorsal ribs support epipleural appendages, in this family, 
anchylosed to the posterior margins of these bones, below the middle 
