MOEPHOLOGT OF THE OWLS. 21 



extreme postero-external, instead of on the extreme posterior end of the rod. Viewed 

 from above, it will be seen that a strap-sliaped bar has been developed from the mesial 

 border of the rod, and that this runs forwards and inwards to form a support for the 

 vomer. Immediately behind this process will be found a degenerate hemipterygoid. 



The pterygoid differs from that of the adult only in so far as the articulation with the 

 palatine is concerned. In the young Owl, as in other Neognathse, it is only very 

 imperfectly formed. Viewed from above in a half-grown nestling of Syrnium (Brit. Mus. 

 n. 99.7.19.1), the main shaft may be clearly distinguished from a hemipterygoid rela- ,>,, ^^, ^T^O 



tively large but which yet fails to reach the vomer. The hemipterygoid rests upon the 

 mesial border of the palatine, and extends backwards to be received into an indistinct 

 cleft in the main shaft. The palatine immediately behind the hemipterygoid extends 

 backwards as far as the lower lip of the cleft. Ultimately a synovial joint is formed 

 with the palatine and pterygoid shaft, whilst the hemipterygoid, by fusion with the 

 palatine, disappears. The method of articulation recalls that of the Sphenisci. 



The dentary resembles that of the adult skull. 



The splenial is still distinct : in the youngest skulls it is of considerable size, termi- 

 nating posteriorly on a level with the lateral vacuity, and anteriorly near the distal fifth 

 of the ramus. 



The coronoid overlaps the proximal end of the lateral vacuity, and posteriorly takes 

 part in the formation of the internal angular process. 



The angular forms the inferior border of the proximal end of the ramus, and extends 

 forwards nearly as far as the distal extremity of the splenial, turning inwards on its way, 

 so that whilst the proximal half of the ramus has the inferior border formed by the 

 angular, this border for the anterior half is formed by the dentary. 



The supra-angulare passes forwards between the dentary on the one side and the 

 splenial on the other. 



IV. The Vertebral Column, with Remarks on the Excalation 



OF Vertebr.e. 



All the presynsacral vertebrae are free ; the thoracic are heterocoelous. In general 

 shape they resemble those of the Ealconiformes rather than those of the Caprimulgi, 

 but they possess characters which distinguish them from both of those groups. These 

 distinctions, however, are so slight that they only hold good when the vertebral column 

 as a whole is compared, single vertebrae being frequently easily confounded either with 

 the Palconiform or Caprimulgine vertebra), according to the particular peculiarities. 

 Generally speaking, the vertebrae of the Strigcs are rather less pneumatic than those 

 of the two groups above mentioned. The pleurosteites, and the diapopliyseixl lamellae 

 with which they fuse, form in the Striges a narrow and well-defined outstanding 

 projection on either side of the anterior end of the centrum, sharply contrasting with the 

 centrum itself, which is, as in the Caprimulgi, relatively slightly longer than in the 

 Ealconiformes. Hyperapophyses, so consioicuous in the cervicals of the larger Ealconi- 

 formes, are wanting or only feebly developed in the Strigcs. 



The neural arches of the atlas rise almost straight upwards above the centrum, and 



