AND DEVELOPMENT OF THE BIRD'S SKULL. 127 



a median septo-niaxillary, which runs from the parasphenoidal beak to the bony septum 

 nasi, above the posterior yomer. The os uncinatum is not distinct in these Hornbills, 

 but the ecto-ethmoid terminates in a large pedate process which binds upon the zygoma ; 

 their lacrymal is aborted, and the large lateral ethmoid comes to the outside and top of 

 the face, as in Megalcema and the Passerinae. With the complete ankylosis of the pala- 

 tines at their commissure, nothing can be learned from the adult as to the existence of a 

 medio-palatine keystone. 



In the most exquisite of all vertebrate skulls, that of the Toucan (Ramphastos toco), 

 the structure largely agrees with the " Buceridae." The ecto-ethmoid projects as in them 

 and the Passerinae, and the os uncinatum is represented by the pedate angle of that bony 

 plate. I see a small lozenge-shaped subcarinate vomer below the level of, but acting as 

 a secondary keystone to, the palatine commissure ; this, however, is only the posterior 

 vomer. The anterior piece is a broad bifid ragged wedge of bone, with its narrow angular 

 end dovetailed in between the palatines, immediately above the small spiny semidistinct 

 interpalatines ; its position is transversely vertical, and its size ten times that of the 

 hinder piece. The notch is complete that forms the wide hinge between this marvellous 

 face and skull ; it is T| inch across, and the beak of the parasphenoid is but little behind 

 a descending plate of bone, the sharply bifid middle portion of which is the posterior 

 angle of the nasal septum. The anterior vomer reaches upwards to these three bony 

 spikes by its ragged split upper end. The nostrils are nearly half an inch apart on the 

 upper surface, close in front of the hinge, and overshadowed by the rounded posterior 

 margin of the elevated beak. The thoroughly ossified alae nasi enclose a transversely 

 oval nostril ; the other parts of the nasal labyrinth are all ossified, and the inferior 

 turbinals are exquisite little scrolls of scabrous bone, almost pisiform, and vertically 

 placed, the end of the scroll being seen from below instead of in front as in other birds. 

 Between the splintery prepalatines and the maxillary synostosis there is a rather large 

 oval space ; behind, the palatines are fused together. 



The transpalatine region, with its retral spike, is something between what we see in 

 Megalcema (Plate XXIII. fig. 4) and in Dacelo (Huxley, op. cit. p. 447, fig. 29, PI). The 

 basipterygoids are small rudiments ; the pterygoids are spongy, and have a small epi- 

 pterygoid lobe. This short initial description may help the student to decipher the 

 morphology of this culmination of the " Coccygomorphse." I have just referred to Pro- 

 fessor Huxley's good woodcut of the palate of Dacelo ; in my specimens of the " Alcedinse," 

 namely, Alcedo ispida, XJpupa epops, Todus viridis, I see no vomer. These skulls are 

 thoroughly " Desmognathous," and are especially interesting as to their palatines, in 

 which the transpalatine sends backwards a spike, equal, in Alcedo, to the prepalatine 

 style in front ; in the young Hoopoe the transpalatine is obliquely set on to the palatine 

 as a distinct bone. 



In the " Musophagidee " the os uncinatum attains its fullest development as an anterior 

 transverse bone (see Dr. Beinhardt's paper, already quoted). In a species of Corythaix 

 (? buffoni) there are two medio-palatines and a posterior vomer ; these lie behind the 

 short sutural commissure, in fibrous tissue ; for, posteriorly, the rounded palatines are 

 wide apart, exposing the parasphenoid. 



