SHUFELDT.] OSTEOLOGY OF THE SPEOTYTO. 59? 
sphenoids and the ali-sphenoids share the same fate with tiie bonesthat 
surround them. They form the larger part of the posterior wall of the 
orbital cavities. With the body of the bone the ali-sphenoids assist in 
closing in the tympanic cavities. We cannot positively state that this 
owl possesses a true boney vomer. The ‘‘ pterapophysial” processes of the 
basi-sphenoid are present; they are short, thick, and elliptical on section, 
erowned by facets of the same figure at their distal extremities, which 
look downwards, forwards, and outwards, articulating with a similar 
facet at the middle third and posterior border of each pterygoid. The 
bone also presents for examination the usual nervous and arterial foram- 
ina and grooves for the Eustachian tubes, the foramina being particu- 
larly worthy of notice’on account of their marked individuality, all of 
them being distinct and nearly circular. The tympanics are free bones, 
and carry “out all the usual functions assigned to them. The mastoid 
condyle is long, affording by its extension an additional margin at the 
under side at the end of the bone for attachment of the ear-drum; the 
neck between it and the orbital process is somewhat constricted, and 
presents a large pneumatic foramen on the inner surface. The pointed 
orbital processes extend upwards, forwards, andinwards, slightly clubbed 
at their extremities; they project into the space half way between the 
pterygoid and wing-like post-frontal. The mandibularcondyle is double; 
the inner one is a semi-ellipsoid, placed transversely ; the outer an irreg- 
ular figure, and separated from the inner by a shallow pit. The oval, 
cup-shaped cavity for the reception of the tympanic extremity of the 
squamosal looks directly forward. Between the orbital process and inner 
mandibular condyle, on the free edge of the bone, is seen a small artic- 
ular surface for the tympanic extremity of the pterygoid. The pterygoids 
diverge from each other towards the tympanics by a very open obtuse 
angle. They are slender and seale-like, being compressed from above 
downwards, twisted on themselves at their tympanic extremities, caus- 
ing the long axis of the articular facets for the articulation with these 
bones to be vertical. As already described, they have a mid-posterior 
facet, which meets the pterapophysial process of the basi-sphenoid. An- 
teriorly they do not touch each other, but articulate with the extremities 
of the palatines, and the combined four bones touch, and in the living 
bird glide over for a limited distance the lower border of the rostrum of 
the basi presphenoid. The anterior ends of the palatines articulate by 
an anchylosed schindylesial articulation between the lower surfaces of 
the maxillaries and the thin upper surface of a bony process extending 
backwards from the intermaxillary. From this point they slightly di- 
verge from each other and become broader, being broadest about their 
middles; they then rather abruptly approach each other posteriorly, where 
they form the joint with the pterygoids already described. Their pos- 
terior ends are kept slightly apart by the lower border of the presphe- 
noid. They are flattened from above downwards throughout their en- 
tire extent. Their outer borders are sharp, and form from one end to 
the other a long convexity. As the inner and concave borders ap- 
proach each other posteriorly they develop a raised rim on their under 
sides, thereby affording a greater surface for muscular attachment. 
Above, near their middles, they aid the maxillaries (and in large part de- 
veloped from them) in supporting on either side an irregular spongy bone, 
that serves the double purpose of narrowing the apertures of the poste- 
rior nares and adding bony surface to the roof of the mouth by constric- 
tion of the palatine fissure.! As is the rule in nearly: all birds, the tym- 
~ \These are the maxillo- palatines of Huxley, and the reader is referred to that au- 
thor’s invaluable paper upon the Classification of Birds, ete. Proc. Zool. Soc. Lond., 
1867, p. 441, where these bones are shown in Otus vulgaris, fig. 26. 
