588 Transactions of the Royal Society of South Africa. 
of the head of the bone. Incisura capitis is deeply sculpt as in most parrots, 
and this renders the tuberculum internum rather prominent. The excavation 
or fossa in which the pneumatic foramina are found is circumscribed, the 
crista inferior being short and projecting. 
At the distal end the oblique or radial tubercle is particularly well 
developed as in other parrots, as is the ulnar trochlea on the other aspect of 
this end of the shaft of the bone. 
In the antihrachium or forearm the radius is a wonderfully straight bone, 
while, on the other hand, the ulna is considerably bowed, and shows but very 
faintly down its shaft the papillae for the insertions of the quill-butts of the 
secondary feathers of the wing. Carpus has the two bones found in the 
wrist of all birds — namely, the radiale and the ulnare ; they require no 
special description, though doubtless they exhibit some morphological 
diiferences in the various species of the Psittaci of the world's avifauna. 
Radius has a length of 4 cms. and the carpo-metacarpus of 2 3 cms., the 
humerus striking an average with a length of 3*5 cms. The main shaft 
of the carpo-metacarpus is straight and comparatively stout, while that of 
medius digit is slender and slightly bowed at its proximal third. 
For the rest, the skeleton of manus presents nothing exceptionally 
peculiar, or what I have not elsewhere invited attention to in my previous 
writings. 
In some parrots (Amazo7ia,, etc.) and macaws (Ara), at the distal end of 
the carpo-metacarpus, on the palmar side, one of the muscular grooves is 
bridged across transversely with a small bridge of bone, and a knowledge of 
the presence of this character may, in some iu stances, help out in making 
references of fossil psittacine carpo-metacarpi. 
Ara has the expanded part of the proximal phalanx of medius digit 
perforated by two foramina, and the vacuities, as a rule, do not occur in 
ordinary parrots. 
Claws do not appear on any of the digits of manus. 
The Pelvic Limh. — There are some good distinctive characters in the 
skeleton of this limb among parrots, and, as a rule, these are present in the 
majority of the representatives of the group. 
With respect to pneumaticity, it seems to be restricted to the femur in 
Palaeornis docilis, while in the big macaws (Ara chloroptera) the bones of 
the entire pelvic limb appear to enjoy that condition, all to the pedal 
phalanges. None of the bones of this limb are pneumatic in Cacatua 
leadheateri, and this may be true of other cockatoos not examined by me. 
Returning to the femur of Palaeornis docilis, it is to be noted that its 
subcylindrical shaft is quite straight, smooth, long, and slender. Proximally, 
the usual characters there seen are but feebly developed, as I find the caput 
femoris small and sessile, and the trochanter major much reduced at the 
summit as well as on the anterior aspect. It rises not at all above the 
