1889.] MR. W. K. PARKER ON STEATORNIS CARIPENSIS. 169 
weak in Steatornis ; in this respect also it resembles the Owls. But 
it is evident that they can exert a considerable amount of force in 
tearing to pieces the fruits on which they feed; about equal, perhaps, 
to that of which an Owl is capable, whose food, however, is not ripe 
fruit, but small living vertebrates. 
Before finishing my description of the oral apparatus, there are 
several things to be mentioned in the upper and hinder parts of the 
skull proper; besides the “remnants”? of the larval palatines, or 
ossa uncinata. 
These latter structures (Plate XVII. figs. 1-3, 0.u.) are attached 
to—grow directly out of—the hind wall of the nasal capsule (pars 
plana, or ectoethmoid, p.p.). The whole of this wall is an oblique 
tract of bone 9 millim. deep and 5 millim. wide ; it is notched deeply 
in its fore edge, at the middle; the part above the notch is the ali- 
ethmoid ” (al.e.), the back part of the region of the upper turbinals ; 
and the lower part, or pais plana, is the back of the middle turbinal 
region. ‘There are no special turbinal coils to increase the surface for 
the distribution of the Ist, or olfactory nerve; the aliethmoid merely 
forms a semicylindrical fold, which runs inwards and forwards from 
the notch between the upper and lower regions. The aliethmoid is 
confluent above with the frontal roof, and behind it there is a 
trilobate fenestra, 6 millim. long and 3 millim. deep. This latter 
space is the membranous representative of the outer wall of the cribri- 
form plate of a Mammal; the olfactory crus (I.) runs along through 
it to the simple nasal labyrinth. In all these things this bird is 
normally ornithic. The olfactory crura are separated by the thick 
top of the mesethmoidal partition wall (p.e.), the fore edge of which 
forms the hinder boundary of the great notch, which gives rise to— 
makes possible—the fronto-nasal hinge. The aliethmoid, at its anky- 
losis with the frontal roof, is grooved by the ophthalmic, or orbito- 
nasal nerve, which runs, outside the olfactory crus, into the nasal 
labyrinth, to supply its antero-inferior region, to which the nerve 
of smell does not come. On the right side one, on the left two, 
small perforations are seen at the root of the pars plana. 
Now this ectoethmoid (pars plana) %s continuous with the an- 
terior crus of the cartilaginous palato-quadrate arch in the Tadpole, 
and also in the adult Frog: in the Salmon and other Teleostei, and also 
in the Urodeles, this crus articulates with the ectoethmoid. The 
fore part of that arch is naturally divisible into three regions, 
namely—the ethmo-palatine, pre-palatine, and post-palatine. Here 
in Steatornis, and also in Todus, the part called the “os uncinatum ” 
—so well known in Musophagidee—is triradiate ; thus it has all the 
three regions seen in its homologue in the Ichthyopsida. Of course 
it is small, and degenerates into membrane at the end of its rays; but 
it is an extremely archaic,—a truly primitive structure, and is built 
up amongst the newer, functional parts of the palate. In passing, I 
may state my experience of the presence of this almost functionless 
remnant. It is well developed in Steatornis, Todus, the Musopha- 
gidze generally, in Scythrops, where it is very large and perfect, and 
in Piaya cayana, where it is a simple vertical needle of bone; is 
