36 EDWARD A. WILSON. 
for though the basal half is still white, the terminal half is divided equally into 
black and vivid orange, the orange pigment completely occupying the terminal quarter 
of the feather. 
It is noticeable, too, that in the Emperor Penguin the immature birds show 
precisely the same pale pearly-grey coronal patch that is found in the immature 
King, though the changes are not continued in the adult Emperor as they are in 
the adult King. 
In this respect, therefore, namely, the development of golden superciliary feathers, 
the King Penguin forms a very definite intermediate link between the Emperor and 
the group Megadyptes, while the golden band in Megadyptes still further developes into 
long golden plumes of Catarrhactes. 
Pygoscelis, [ am told by Mr. Pycraft, shows certain skeletal characters which are 
yet more primitive than those of Aptenodytes, so that while there appears to be some 
reason for considering the Emperor Penguin to be a more primitive type than the 
King, and Megadyptes more primitive than any form of Catarrhactes, Pygoscelis may 
be considered the most primitive of all. And further, in Catarrhactes, judging from the 
development of the superciliary tract of feathers, C. pachyrhyncus and C. sclateri are 
less specialised forms than C. chrysocome, while C. chrysolophus and C. schlegeli are 
more specialised than any of them, not only on account of the length of their super- 
ciliary plumes, but also because the golden bands meet anteriorly in the middle line, 
of which there is no tendency in the Snares example of Aptenodytes patagonica. 
It will be seen from the above that this one specimen may be considered to 
be a key to the whole question, if the head, as I am inclined to think, is in all the 
penguins the part in which both generic and specific distinctive characters are specially 
developed, as being the part mainly visible for recognition when these birds are floating 
on the surface of the water. 
z 
PYGOSCELIS ADELIA. 
The Adélie Penguin. 
(Plates [X., X.) 
Catarrhartes adelic, Hombr. and Jacq., Ann. Sci. Nat. (2) p. 320 (1841). 
Pygoscelis adeliw, Coues, Proc. Ac. Philad. (1872), p. 196; Sharpe, Rep. ‘Southern Cross’ Coll., (1902), 
p. 118, ibigue citata ; Hagle Clarke, Birds of South Orkney Ids., [bis., Jan., 1906, p. 157, pl. viii. 
List oF MATERIAL IN THE ‘ DiscovERY’ COLLECTION. 
No. 52, 6, ad. skin. Nov. 7, 1902. McMurdo Sound. Weight, 11 Ibs. 
No. 58, 6, ad. skin. Nov. 7, 1902. do. 
No. 54, 9, ad. skin. Jan. 2, 1903. do. See Birds, Pl. IX., fig. 5. 
No. 55, g, ad. skin. Nov. 7, 1902. do. 
No. 56, 9, ad. skin. Dec. 22, 1902. do. 
No. 57, g, ad. skin. Dec. 23, 1902. do. 
No. 58, imm. skin. Jan 9,1903. Cape Adare—shedding the down. See Birds, PLIX., fig. 3. 
No. 59, 9 imm. skin. Jan. 27,1904. McMurdo Sound—about to moult. 
