oO Sclater on the Sy sterna Avium. 



has caused Sundevall to place them at the end of his division 

 Psilopredes*), and, no doubt, belong to a new line of departure 

 from the Passeres towards the Gallinre. It is very hard to have 

 to mar the symmetry of the Columbine group by adding to it the 

 Pteroclidfe. Yet there can be no doubt that in most respects the 

 Sand-Grouse are more truly Pigeons than Grouse, and that the 

 only way to escape from the dilemma is to recognize the Ptero- 

 cletes as a separate order, as Prof. Huxley has proposed to do,"} - 

 intermediate between the Columbse and Gallinse. 



As regards the divisions of the Columbae into families I have 

 recognized two in the last edition of the 'List of Animals' — 

 Carpophagidae and Columbidaa. To these should have been 

 added a third (Gouridae) for the Crown Pigeons, in which the 

 tarsi have a very peculiar conformation, and perhaps a fourth 

 (Didunculidae) for Didunculus. 



The Dodos must be held to belong to quite a separate section 

 of the order. 



12. (JAi.i.ix.K. and 13. OPISTHOCOMI. 



As regards the true Gallina-. which we now come to, we can- 

 not do better than adhere to Prof. Huxley's excellent division of 

 them into Peristoropodes and Alectoropodes. In the former sec- 

 tion I have recognized two families. Cracidae and Megapodiidae ; 

 in the latter two also, Tetraonidae and Phasianidae. Whether 

 the Meleagrina' and Numidinae should stand as subfamilies of the 

 Tetraonidae (as arranged in the ' List of Animals' for 1879), or 

 as separate families, is, I think, not quite certain. The Turnici- 

 dae, there treated as only a family of the Gallinse, as also Opis- 

 thocomus, must. I think, after Prof. Huxley's elaborate discussion 

 of the subject,]; ^ e definitely constituted as separate orders, Hemi- 

 podii and Opisthocomi — the former leading off towards the Cryp- 

 turi, the latter most nearly allied to the Cracidae, and also showing 

 manifest signs of alliance with the Coccyges among the Picaria-. 



14. Geraxomorphj:. 



In the v Nomenclator ' I have placed the Rails next after the 

 Gallinre. to which they show manifest symptoms of relationship. 



* Tentamen p. 97. t P. Z. S. 1868, p. 254. 



+ P. Z. S. 1868, p. 311. 



