454 I'ROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. [Apr. 11, 



Nj/ctidmsjamaicc77sis. 

 View of the palate without the ]3terygoicl bones. The letters as before. 



longer and narrower than in the Swifts or the typical Passerine 

 birds.. The expanded inner ends of the slender and characteristically 

 Passerine maxillo-palatines are quite distinct from the vomer and 

 ■Voni one another. 



Caprimulyiis further presents a remarkable contrast to the Swifts 

 and all the true Passeres in having well-developed basipterygoid pro- 

 cesses. These are absent in JEyotheles novcB-hollandice, the palate 

 of which is intermediate between that of the Goatsuckers and that 

 of the Swifts. 



Nyctibius closely resembles Caimmulgus, even to possessing the 

 very peculiar division of each ramus of the mandible into two por- 

 tions, the one of which is moveable upon the other, pointed out in 

 the latter genus by Nitzsch. But the slender anterior processes of 

 the palatines are closely approximated in the middle line, instead of 

 remaining widely separated as in Caprimulgus and Trochilus ; and 

 the maxillo-palatines are closely adherent to them and to the vomer, 

 though a true anchylosis does not appear to have taken place. 



Trochilus has the true Passerine vomer, with its broad and trun- 

 cated anterior, and deeply cleft posterior end. I have not yet been 

 able to obtain a perfectly satisfactory view of the structure and 

 arrangement of the palatine bones in the Humming Birds. 



That the birds of which I have spoken under the four heads of 

 DromcBognathoiis, Schizognathous, Desmognathous, and ^githogna- 

 'hous really possess the various arrangements of the palatine and 

 adjacent bones which I have described, is a matter of observation 

 which readily admits of confirmation or the reverse. It is another 

 and very important question whether these cranial characters may 

 safely be taken as indications of natural affinities ; and I now pro- 

 pose to make a few remarks on that point. 



It will not, I think, be disj)uted by any ornithologist that the 

 Schizognathous birds constitute a very natural assemblage. Taking 



