38 ME. W, P. PYCEAFT ON THE 



e. Palatines with posterior lateral border convex ; vomer large, filling space between 



maxillo-palatines ; interorbital region behind lachrymal less in breadth than the 

 distance from nasal hinge to anterior angle of anterior nares ; processus lateralis 

 basalis of coracoid straight, and extending beyond level of anterior lateral process 

 of sternum S. perlatus. 



f. Palatine with posterior lateral border nearly straight j vomer large ; pterygoid of 



great breadth distad of basipterygoid facet ; lachrymal large and with very 



shallow lachrymal groove S.javanicus. 



XI. Summary. 



It is doubtful whether, on the evidence of the skeleton alone, the Striges would ever 

 have been separated from the Falconiformes, their resemblance osteologically to the 

 Accipitres being most striking. The anatomy of the soft parts, however, shows 

 conclusively that there is no real affinity between these two groups. The hind limbs of 

 the Accipitres and the Striges, as Dr. Gadow has pointed out ( 1 2), are almost indistin- 

 guishable, yet the former has an ambiens muscle, the latter has not. Again, he reminds 

 us, that though both Accipitres and Striges are carnivorous, yet the former have vestigial 

 caeca and the latter extremely large cseca. In this absence of an ambiens, the form and 

 size of the coeca, and in the convolutions of the intestines, according to Mitchell, we have 

 a combination of characters agreeing more nearly with those of the Caprimulgi than with 

 those of any other group. The pterylography also points to the same conclusion. Again, 

 as in the Caprimulgi, the skull is often extremely pneumatic, e. g. Strix, Asio, Photodilus ; 

 whilst the peculiar form of the lachrymal of the Striges is met with elsewhere only 

 among the Caprimulgi. The same may be said of the suppressed lachrymo-nasal fossa 

 and the basipterygoid processes. The general character of the sternum is also Capri- 

 mulgine, though, strangely enough, the pelvis is most remarkably Accipitrine. The 

 form of the anterior palatal fossa is peculiar to the Owls. 



A comparison between the skull of a very young nestling Syrnium or Bubo with a skull 

 of similar stage of development of Steatornis will reveal some striking similarities of 

 structure which will still further aid in establishing the Caprimulgine theory of origin of 

 the Striges. 



It will be remembered that in the first part of this memoir, in which the pterylological 

 characters were dealt with, this group seemed to fall naturally into two families, the 

 first containing the Barn-Owls only, the second all the remaining forms; these were 

 further divisible into two sub-families — the Asioninse and the Nyctalinae. 



Judging by osteological characters alone, the main division into families still holds good, 

 but it would appear to be necessary to recognize about six sub-families belonging to the 

 Asionidae, instead of two. This subdivision, it shovild be remarked, would be founded on 

 the characters of the skull only, the axial and appendicular skeletons being remarkably 

 alike in all the members of the family. 



The six sub-families would be : — ■ 



1, Asionina3. 



2. Photodilinse. 



