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, o.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 miUim. deep and 5 niillim. wide ; it is notched deeply 

 in its fore edge, at the middle ; the part above the notch is the ali- 

 ethmoid " {ale.), the back part of the region of the upper turbinals; 

 and the lower part, or pars plana, is the back of the middle turbinal 

 region. 'I'here are no special turbinal coils to increase the surface for 

 the distribution of the 1st, or olfactory nerve ; the aliethmoid merely 

 forms a semicyUndrical 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 miUim. 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 cms (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/ronto-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 re^on, 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) is 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-pa'latine, and post-palhtine. Here 

 in Steatornis, and also in Todus, the part called the "os uncinatum " 

 —so well known in Musophagidae — is triradiate ; thus it has all the 

 three regions seen in its liomologue 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- 

 gidiB generally, in Scythrops, where it is very large and perfect, and 

 in Piaya cayana, where it is a simple vertical needle of bone ; is 



