176 ME. 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 tlie 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 pei'fectly 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. The optic foramina are distinct 

 and raised high above the rostrum, as in JEpyornis. 



^pyornis and Binornithidce 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 yEpyornis, as in Struthio, the optic foramen is raised liigh 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 Dinornithidw the optic foramina are deeply overhung by the outstanding orbito- 

 sphenoids ; in this respect resembling Aj)teryx. 



In Apteryx the orbits are small and tubular, without post- or pre-orbital processes, 

 and the interorbital region of the frontals I'educed 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 Divornithidce 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 Lromceus and J^pyornis 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 iv. 

 (pathetic) lies mesiad of and slightly above the in., being divided only by a narrow bar 

 of bone from the 11. (optic). The III. oculo-motor lies directly below the iv. ; like the 

 IV. it is only separated from the il. by a narrow bony bar. Lowest of all, and forming a 

 triangle with the in. and vi. foramina, lie the foramen for the arteria ophthahnica interna. 



