THE CLASSIFICATION OF BIRDS 35 



basipterygoid processes * present ; the oil-gland tufted ; and the 

 young prascccal. 



Grues. Charadriiformes with the spinal feather-tract not 

 defined on the neck ; the dorsal vertebras heterocoelous ; [the 

 basipterygoid processes generally absent, but occasionally present ;] 

 the young prascocal ; and the oil-gland tufted. 



Pterodes. Charadriiformes with the spinal feather-tract not 

 defined on the neck ; the dorsal vertebras heterocoelous ; the basi- 

 pterygoid processes present ; the oil-gland nude ; and the young 

 praecocal. 



Columbce. Charadriiformes with the spinal feather-tract well 

 defined on the neck ; the dorsal vertebrae heterocoelous ; the basi- 

 pterygoid processes present; the young altrical; and no down 

 retained in the adult plumage. 



11. GAVLE. 12. LIMICOL^L 



The Gavias and the Limicolas have characters in common 

 which are not shared by the three other Orders, and might 

 almost be joined together in one Order. They have opisthocoelous 

 dorsal vertebras, and the spinal feather-tract is well defined on 

 the neck by the lateral bare tracts.-f* The spinal feather-tract is 

 also well defined on the neck in the Columbas, but the lateral bare 

 tracts are confined to the base of the neck in the Pterocles and 

 the Grues. The Pterocles further differ from the Columbae in 



* The presence or absence of basipterygoid processes cannot be regarded as 

 of much taxonomic value. Inasmuch as they are characteristic of Lizards, 

 Snakes, and archaic Reptiles, and are found in the embryos of many Passeres, 

 their presence must be regarded as a primitive character which might easily be 

 independently lost by various groups of birds. There is every reason to believe 

 that they have been thus lost by the majority of birds. 



They still survive amongst the Charadriiformes in the Limicolae, Pterocles, 

 and Columbae. 



Amongst the Ciconiiformes they are only known in the Anseres. 



Amongst the Falconiformes they survive in the Puffinidce, Gypogeranidce, and 

 the Striyidce. 



Amongst the Coraciomorphae they are only known in the Caprimvlgidce, the 

 Steatornithldce, the Cathartldce, and the Trogonidce. 



Amongst the JEgithomorphae they occur in the Turnices, the Crypturi, and 

 the Gallinae. 



All the Dromaeomorphae possess basipterygoid processes. 



t Nitzsch asserted that Rhynchcea was exceptional in having no lateral bare 

 tracts on the neck, and later writers have copied his statement. I have exa- 

 mined skins of Jthynchcea capensis and they appear to have the same lateral 

 bare tracts on the neck as are found in Scolopax. 



