176 MR. W. P. PYCRAFT ON THE MORPHOLOGY AND 
arching the orbits are short and blunt, but are connected with the frontals by a more 
or less imperfect chain of supra-orbital ossicles, as in the Crypturi. Generally it 
would seem, from the number of skulls which I have examined, that these supra- 
orbitals fuse completely with one another and the lachrymal and frontal so as to 
obliterate all trace of their independence. A specimen in the Rothschild Museum, 
however, has this chain on one side perfectly developed (Pl. XLII. fig. 3). The 
existence of this supra-orbital chain seems to have escaped the notice of all recent 
writers. On looking up the subject I find it was first described by Cuvier [14] in 1799. 
Hildebrand [37] in 1806 seems to have rediscovered them. Meckel [56] and other 
writers at the beginning of the century were also aware of their existence. 
There is a distinct, but small, pre-sphenoid fossa. he optic foramina are distinct 
and raised high above the rostrum, as in @pyornis. 
Aipyornis and Dinornithide agree in the form of the supra-orbital ledge. The pre- 
orbital region of this is formed externally by the lachrymal, which has completely 
fused with the frontal to form one uniform plate of bone. This is just what would 
happen in Struthio if the fossa between its backward spur and the nasal were 
filled up. 
In Apyornis, as in Struthio, the optic foramen is raised high above the level of the 
parasphenoidal rostrum. Below the lacerate fossa, and between it and the trigeminal 
foramen, the surface of the combined alisphenoid and pre-temporal wing is much 
inflated and roughened by numerous elongated spine-like processes for the attachment 
of muscles. 
In Dinornithide the optic foramina are deeply overhung by the outstanding orbito- 
sphenoids; in this respect resembling Apteryz. 
In Apteryx the orbits are small and tubular, without post- or pre-orbital processes, 
and the interorbital region of the frontals reduced to its smallest possible limit. 
In Crypturi there is no lacerate or pre-sphenoid fossa or post-orbital process; the 
pre-orbital backward spurs of the lachrymal are wanting, and the interorbital region 
of the frontal is deeply notched, being cut away to within a short distance of the 
interorbital septum. 
The lacerate fossa in some Dinornithide takes the form of a deep pit; generally, 
however, it is represented only by a shallow depression. In and around this lie certain 
of the cerebral nerve-apertures worthy of note. 
In Dromeus and Ajpyornis these are very distinct. In the former those of the 
first division of the v. (orbito-nasal) and the vi. (abducent) nerves lie, the latter below 
and slightly mesiad of the former, and both external to the rest. That of the rv. 
(pathetic) lies mesiad of and slightly above the 111, being divided only by a narrow bar 
of bone from the 1. (optic). The 111. oculo-motor lies directly below the rv. ; like the 
Iv. it is only separated from the mu. by a narrow bony bar. Lowest of all, and forming a 
triangle with the mt. and vi. foramina, lie the foramen for the arteria ophthalmica interna, 
