396 STRUCTURE AND CLASSIFICATION OF BIRDS 



Hesperornis 



Divers Grelies 



14, 15 17-21 



+ 



Gerv. vert. . . 17 



Gatwpoph. canal . . 



HcBtnap. . . . . ' With expanded i With expanded Not so expanded 



ends I ends at ends 



Dors. vert, fused . \ None I None Several 



Patella . . \ Large Very small Large 



Supra-orbit. grooves 1 Large • Large Not marked 



With the grebes Hesperornis agrees in only two of the 

 characters, and in the remaining four with the divers. It 

 presents in fact, as might be expected of so ancient a form, a 

 compound of the grebe and the diver. 



We cannot however, in my opinion, put it down defi- 

 nitely as the ancestral form whence both divers and grebes 

 have branched off; but it seems to approach that form, 

 agreeing as it does in most points with the more generalised 

 divers.^ 



SPHENISCI ^ 



Definition.— 'Moderately sized to large birds, with wings modified to 

 form a swimtuing paddle. Aftershaft present. Feathering 

 continuous. Oil gland tufted. Muscle formula of leg, ABX + . 

 No biceps brachii or expansor secundariorum. Two carotids. 

 Skull schizognathous, holorhinal, without basipterygoid pro- 

 cesses. Dorsal vertebrae markedly opisthocoelous. Scapula 

 flattened and expanded. Metatarsals short and incompletely 

 fused. 



The anatomy of the penguins has been mainly investi- 

 gated by Menzeiee ^ and Watson.^ The group, which is 

 entirely antarctic, contains the genera Eudyptes, Aptenodytes, 

 Pygosceles, and Spheniscus. 



' For discussion of the affinities of the Hesperornis see, besides Mabsh and 

 PtjKBKiNGEB and Gadow in their large works, Fubbeingek, ' Ijber die syste- 

 matische Stellung der Hesperornithidffi,' Orn. Monatsschr. d. detUsch. Ver. s 

 Schutz. VUgel, xv. 1890, p. 488 ; F. Helm, ' On the Affinities of Hesperornis. 

 Nature, xliii. 1891, p. 368 ; Shufeldt, ' On the Affinities of Hesperornis,'' ibid. 

 p. 176 ; D'A. W. Thompson, ' On the Systematic Position of Hesperornis,' Stud. 

 Mus. Univ. Coll. Dundee, i. 1890. 



^ Since Watson's ' Egport on the Penguins collected by the Challenger 

 the following papers have appeared : M. Menzbiee, ' Vergleichende Osteologie 

 der Penguine,' &c.. Bull. Sue. Imp. Nat. Mosc., 1887; H. Schauinsland, ' Zur 

 Bntwiokelung des Pinguins,' Ver'h. Ges. Deutsch. Naturj. Leipzig, 1891, p. 135 ; 

 Studeb in Zoology of S. M. S. ' Gazelle.'' 



