24 



THE VOYAGE OF H.M.S. CHALLENGER. 



on the other hand, the costal processes are relatively of much smaller size, and are 

 directed more horizontally outwards, so that their inner borders form nearly a right line 

 with the anterior sternal border. 



In both Eudyptes (PI. VI. figs. 1, 2, 7) and SpJieniscus (PI. VI. fig. 8) the costal 

 processes present an intermediate form. They are relatively of the same size as in 

 Aptenodytes, but are directed less obliquely outwards than in Pygosceles. 



Apart from size, I could distinguish in the sternum no features characteristic of the 

 species of the different genera, except in Spheniscus demersus, in which the costal pro- 

 cesses are completely perforated by a foramen, which in other species is only represented 

 by a depression on the lower surfaces of these processes. 



The accompanying table shows the chief dimensions of the sternum of diflferent species 

 in inches. 



APPENDICULAR SKELETON. 



The Anteeior Extremity. 



The Scapida. 



The scapula in every species of Penguin is, relatively to the other parts of the 

 skeleton, of larger size than in any other group of bii'ds, and is correlated with the 



