THE CLASSIFICATION OF BIRDS 31 



The range of the Psittaci may be regarded as circumtropical, 

 but the Trichoglossidce are confined to Australasia. 



The Psittaci may possibly be naturally divided into two groups 

 (Salvadori, "Catalogue of the Birds in the British Museum," 

 xx. p. 2). The Nestorince, the Loriince, and the Gyclopsittacince may 

 be associated together to form the family Trichoglossidce (Gadow, 

 " Bronn's Thier-Eeichs," ii. p. 222). In this family the ridges on 

 the^under-surface of the hook of the mandible are indistinct and 

 longitudinal. The Cacatuince, the Psittacince, and the Stringopince 

 may be united to form the family Psittacidce, with the ridges on 

 the under surface of the hook of the mandible more distinct and 

 more or less transverse or oblique. 



6. ACCIPITRES, 



The position of the Accipitres in the Systema Avium is a ques- 

 tion upon which authorities differ widely. Ftirbinger places them 

 between the Steganopodes and the Herodiones, but other writers 

 Express different opinions. 



The Accipitres consist of three families. The Gypogeranidce 

 have long legs like Storks, but differ from them and from the 

 Falconidce and the Pandionidce in having basipterygoid processes, 

 a character in which they agree with the Striges. The Pandionidce 

 agree with the Strigidce, and differ from the Falconidce and Gypo- 

 geranidce, in having no bony bridge over the extensor groove 

 on the anterior surface of the distal and of the tibio-tarsus, and 

 in having a bony bridge over the extensor groove on the anterior 

 surface of the proximal end of the tarso- metatarsus (Milne- 

 Edwards, Oiseaux Fossiles de la France, ii. pp. 413, 419). The 

 Pandionidce also agree with the Striges and the Psittaci, but differ 

 from the Falconidce and Gypogeranidce in having only the second 

 and third digits directed permanently forwards. 



The Accipitres are cosmopolitan in their range, but the Gypo- 

 geranidce are confined to South Africa. * 



' 



7. STRIGES. 



The owls are unquestionably the most aberrant group amongst 

 the Falconiformes. They occupy a similar position to that of the 

 Columbae amongst the Charadriiformes. It is very curious how 

 many characters the Striges have in common with the Caprimulgi. 



