50 A HISTORY OF BIRDS 



gained in size in adaptation to the peculiar feeding habits of 

 their possessors. That this is so a study of the jaws and tongues 

 of the Anseres will show. The lamellae in question are largest 

 in the surface-feeding-ducks, reaching their maximum develop- 

 ment in the Shovellers. In the Geese, which are vegetivorous, 

 the lamellse take the form of horny teeth, and these become 

 still more tooth-like in the piscivorous Ducks. The fact, there- 

 fore, that lamellae of the kind which obtain in the surface-feed- 

 ing-ducks are found also along the jaws of the Flamingoes may 

 mean, either that they have been acquired from the common 

 ancestor of the Storks and Anseres, or that they have been in- 

 dependently acquired. This last alternative seems to have been 

 the case among the Petrels, some of which, as in Prion, have 

 lamellated beaks as well developed as in many Ducks. 



In their pterylosis the Screamers are certainly primitive in 

 that the apteria are but feebly developed, as in the Struthious 

 birds, Divers, and Penguins. They furthermore resemble the 

 Struthious birds in the convolutions of the intestines, and in the 

 structure of the genital organs of the male. But this last char- 

 acter, be it noted, also obtains among the Anseres but not in 

 the Flamingoes, which, according to some, are to be reckoned, 

 as we have seen, among the Anseres. 



As to the Anseres proper but little need be said here. Start- 

 ing with the primitive Palamedea and Chauna we pass to the 

 more typical Anseres which fall into three more or less sharply 

 defined groups^ — -the Swans, Geese and Ducks. Of these prob- 

 ably the Geese are the more ancient, for in one shape or 

 another they retain many characters which must be regarded as 

 primitive. Thus in some genera, e.g., Clcephaga, the nestling 

 wears a striped mesoptyle plumage: Anseranas has only parti- 

 ally webbed feet, and presents other characters indicative of a 

 low position both in the skeleton and the convolutions of the 

 intestines, though in the matter of its strangely convoluted 

 trachea it is highly specialised. The Swans on the one hand, 

 however, and the Ducks on the other must be regarded as 

 offshoots of this Anserine stock. 



We proceed now to a survey of the second great division of 

 the Neognathai ; and commence with that branch which con- 

 stitutes what Dr. Gadow calls the Alectoromorphine legion. 

 First of all must come the Galliformes — Gallinaceous types — 



