EEPOET ON THE SPHENISCID^. 7 



anterior narial apertures considerably exceed in relative length even those of Eudyptes 

 itself. 



The intermaxillary suture is entirely obliterated in every species of Eiidyptes and 

 Spheniscus. In Pygosceles and Aptenodytes it is clearly visible in the upper two-thirds 

 of its length. 



With regard to the relative dimensions of the various portions of the upper jaw, there 

 is a considerable amount of variation in the different genera. In Eudyptes, Pygosceles, 

 and Aptenodytes the frontal processes of the intermaxillary bones, together with the 

 applied processes of the nasal bones which together form the bridge of the nose are 

 relatively narrow, and form a bony bar which, when the skull is viewed from below, 

 does not completely fill the interval between the lateral portions of the upper jaw. In 

 Spheniscus, on the other hand, with the single exception of Spheniscus minor, the bridge 

 of the nose is relatively broader, and completely fills up the interval between, and indeed 

 slightly overlaps the lateral bars of the upper jaw. Spheniscus minor in this respect, as 

 in several others, seems to hold an intermediate position between Eudyj^tes and Spheniscus. 

 In it the bridge of the nose fills up the interval between the lateral bars of the upper 

 jaw, but does not overlap them to the same extent as in other species of Spheniscus. 



The upper jaw, as a whole, differe in form in Eudyptes, Spheniscus, and Aptenodytes. 

 In Eudyptes it is elongated-oval in form, being broadest at the middle, and narrowing 

 both towards its base and apex. In Spheniscus, Pygosceles, and Ap)tenodytes the 

 basal portion of the upper jaw is the broadest part, and from it the beak narrows 

 gradually to a point in front. The very elongated form of the beak in Pygosceles and 

 Aptenodytes at once distinguishes these from the other genera of Penguins. In Pygos- 

 celes, Apteyiodytes, and Spheniscus, moreover, the lateral bar of the upper jaw is relatively 

 narrow, while in Eudyptes it is proportionally broader and stronger. 



The occipital condyle is sessile in every species of Penguin, and the articular surface 

 is almost globular in form. Immediately in front of the condyle the basi-occipital bone 

 presents a deep circular depression into which the musculi recti capitis antici are inserted. 



The basi-sphenoidal rostrum is triangular in form, and narrows in breadth from behind 

 forwards. It is altogether destitute of basi-pterygoid processes in every species of 

 Penguin. 



The pterygoid bones are triangular in form and much flattened from above downwards. 

 Their anterior internal angles articulate both with the basi-sphenoidal rostrum and with 

 the posterior extremities of the palate bones. In Eudyptes the pterygoid bones are 

 relatively shorter and broader than in either Spheniscus, Pygosceles, or Aptenodytes, in 

 all of which the posterior extremities of the bones are slender and elongated. 



The palate bones are oval in form. They articulate behind with the pterygoid bones 

 and coalesce in front with the intermaxillaries. There is no trace of an intermaxillary 

 suture in the adult of any species of Eudyptes or Spheniscus. In Pygosceles and Apteno- 



