134 MR. W. K. PARKER ON THE STRUCTURE 



agrees with a large number of the " Aves aerise," whereas in Hawks and Owls they are 

 both present. But the most striking part of their palatine outworks is the huge 

 maxillary (mx) ; it is, relatively to the premaxillary, as extensively developed as in tbe 

 Chelonia, although the dentary process of the latter bone overlaps it as in osseous Fishes, 

 and, indeed, in birds generally. 



These parts are builded together in a manner which would please the eye of an 

 architect. 



But the whole meaning of these parts can only be seen by the study of sections made 

 in young skulls. In a nestling younger than the one from which the palatal view was 

 taken, I have been able to decipher all those parts of the face in which the nasal capsules 

 have their furniture disposed amongst and within the foremost facial bars. 



In this type the nasal labyrinth enfolds itself and encloses its passages with solid car- 

 tilage to a very unusual extent. Here (Plate XXV. fig. 1, en) the external nasal opening 

 is not a long slit, but a neat round opening ; the rim is wrought, like the rim of a 

 cup, and is almost closed by a finger-shaped projection from the alinasal turbinal (atb). 

 This process looks outwards and backwards, and only leaves around it an oval chink. 

 The whole alinasal region (figs. 1-3, aln) is formed into a pair of oblong oval pouches, 

 like two carpels of an apocarpous fruit dehiscing ; seen from below, there seem to be 

 two cells left out of four; and the still persistent lanceolate prenasal cartilage (pn) 

 running from the base of the septum (sn) carries out still further the similitude, it being 

 in the likeness of the fruit-axis. Behind, at this most bulbous part, these nasal pouches 

 are complete tubes, the floor having coalesced with the middle wall (fig. 3, aln, sn) ; this 

 is shown in section (fig. 5), also the apposition of those parts further forwards (fig. 6). 



When the septum is removed, to show the inner face of the turbinals, it is seen that 

 the alinasal turbinal (fig. 2, atb) is a large leaf of cartilage, hollow outside and bulging 

 within (see also sections, figs. 5 & 6). This leaf is attached to the outer wall by its 

 upper edge, and is also confluent behind with the bulging floor, where that part rests on 

 the nasal nerves (nn). Over the hinder third the true " inferior turbinal " arises ; this 

 is at first a two-winged crest (fig. 5), but further backwards acquires the true type of the 

 organ, as seen in the " Carinatse " generally; it has nearly three coils (see fig. 2,itb). 

 The middle turbinal is merely represented by an irregular ridge on the fore face of the 

 antorbital plate, and the upper turbinal by the coiling, on itself, of the aliethmoidal 

 plates, exactly as in the Common Fowl (Phil. Trans.). 



The septum nasi is connected by an uncleft isthmus of cartilage (fig. 4, sn) with the 

 perpendicular ethmoid ; it is unusually deep and large for a bird (figs. 4-6). There is 

 one septal fenestra (sf) in addition to the " notch " between the septum and the ethmoid ; 

 this window is situate close behind the insertion of the alinasal bag. The hinder inser- 

 tion of that bag is much thickened, and at this part the nasal branch of the orbito-nasal 

 nerve (fig. 4, nn) bores its way through the cartilage,, piercing the alinasal, and bur- 

 rowing in the septal cartilages ; it soon gets below the septum (see figs. 2, 4, 5). Now 

 if these sections be compared with the palatal view (Plate XXIV. fig. 4), and these by the 

 reader with an adult skull before him, it will be easy to comprehend the compact and 

 complex desmognathisrn of this type, a type having the most highly ossified and, in many 



