168 Proceedings of the Royal Fht/sical Societj, 
make upon ifc, I shall adopt the comparisons made by Professor 
Owen on the typical skull of the genus Palapteryx. The 
breadth across the mastoid processes in the mutilated cranium 
from E-otomarrama is 2j7oth inches ; the length of the cranium, 
measured from the upper part of the foramen magnum to the 
anterior extremity of the frontal bone, is Sj%th. inches; the 
breadth across the postorbital processes is 2y%th inches ; the 
breadth across the temporal fossae is 1 yV^hs of an inch. The 
vertical diameter, from the supraoccipital ridge to the basi- 
sphenoid, is l^Vths of an inch. The transverse diameter of 
the occipital foramen is nearly y\ths of an inch. The breadth 
across the paroccipitals is 2-|- inches. The sutures of the skull 
are entirely obliterated ; and from the well marked muscular 
impressions and rugose surface, there is no doubt that it be- 
longed to an old bird. The occipital foramen is subcircular, 
and broadest transversely ; the descending basioccipital is 
impressed by a shallow pit, divided by a slight median ridge, 
and bounded below by the straight posterior border of the 
basisphenoid platform, the outer angles of vv^hich are large 
round tuberosities. The precondyloid foramina are situated 
at the upper and back part of the basisphenoidal protuber- 
ances, midway between the outer edge of the paroccipital ridge 
and foramen magnum, and raised to a level with the lower 
border of the occipital condyle. The precondyloid foramina 
pass obliquely upwards and inwards into the cranium, and 
there are two small pits at the inner and upper edge, nearer 
the occipital condyle. The paroccipital ridges, partly ])roken 
in this specimen, are of a semilunar form, and separated by a 
notch from the basisphenoidal protuberances. The canal for 
the carotid artery is seen grooving the sides of the sphenoidal 
platform, winding round the outer part of the base of the 
sphenoidal protuberances, penetrating the basisphenoid, just in 
front of the lower edge of the paroccipital ridges, and entering 
the cranium by the aperture common to the precondyloid 
foramina internally. The occipital region is divided into two 
parts by a broad median vertical ridge, with two strongly 
marked depressions on each side ; but the subdivision, " slightly 
indicated by the bending down of the supraoccipital ridge," 
in Professor Owen's description of P. gerenoides, is not 
