MR. W. K. PARKER ON THE OSTEOLOGY OF BALAZNICEPS REX. 289 
‘principal frontals.’ In the Heron these processes are bridged over by bone, thus 
walling-in the olfactory nerve. The anterior keeled margin of the pre-sphenoid of Balz- 
niceps is sinuous, but vertical above, whilst its lower half retires a little before coalescing 
with the projecting ‘rostrum.’ In the Heron this centrum retires very much more, and 
the inferior antorbital process, after bridging over the olfactory nerve, sends an elegant 
curled lamina downwards, outwards, and forwards. This process, so large in the 
Albatros and many other birds (¢. g. Snipes, Woodcocks, Pigeons, Goatsuckers, Owls, 
Parrots, &c.), but almost obsolete in the Baleniceps, Boat-bill, and Adjutant, in Gal- 
line, Anatine, and in those wading, swimming, and diving birds in which the orbital 
margin is very incomplete, is a ‘ pterapophysis’,’ and its special homologue may be well 
seen in such mammals as the Rabbit. Serially, it is homologous with those ‘ pterygoid 
plates’ spoken of as pertaining to the post-sphenoidal and occipital centrums. 
The pre-sphenoid of Balzniceps is thick and cellular above, in front, and below ; its 
middle part behind helps the orbito-sphenoid to finish the flat inter-crbital septum. In 
our description of the orbito-sphenoids, we spoke of the deficient ossification of this 
septum ; we will add, that its extreme development, as to thickness and cellularity, is 
in Owls, especially the Screech Owl (Strix flammea), and in Goatsuckers (Caprimulgus). 
In the diurnal Raptores it is more or less imperfect, as also in the Pigeons and Galli- 
nace; in Parrots, Toucans, Woodpeckers, and most of the Scansores, it is very 
perfect, but not in the Hornbills. It is very imperfect in the Corvine, Passerine, and 
Sylviine groups, so nearly related to each other, and so potent in genera and species, In 
the smaller Ardeine birds (e. g. Ardea, Botawrus, and Cancroma), in Cranes, Spoonbills, 
Curlews, Plovers, Godwits, Rails, Coots, Jacanas, Grebes, Divers, Auks, Gulls (the 
smaller species), Gannets, Cormorants, Penguins, Petrels, and even in the Albatroses, 
the inter-orbital septum is more or less incomplete. In the larger relations of Balzeniceps 
this septum is perfect (e.g. Ciconia alba, and in Leptoptilus), and the same may be said 
of the Struthionide. For an account of the manner in which the olfactory chambers 
encroach upon the sides of the pre-sphenoid in such birds as the Ostrich, Dinornis, 
Apteryx, Cassowary, and Dodo, &c., see Professor Goodsir’s paper (op. cit. p. 156). 
We may remark, however, that the Common Duck and the Albatros are familiar but 
very beautiful instances of birds in which these pre-sphenoidal nasal cavities are large 
and well-developed. 
Lacrymal. (Pl. LXV. figs. 1 & 6, 1.) 
The next bone to be spoken of (the lacrymal) belongs properly to the face, but its 
important relations with the sphenoido-frontals and antorbital processes (pterapophyses) 
of the pre-sphenoid make it convenient for it to be dealt with at once. 
1 Where there is a distinct centre for this process, it is something more than a ‘ pterapophysis,’ as may be 
seen in young Pigeons; in these birds it evidently is, what Professor Owen calls it, the homologue of the human 
‘os planum.’ 
