OSTEOLOGY OF THE PENGUINS. 399 



the Spheniscidse, and the long, narrow iWJ^^^U^^ is made of nine 

 more.^ 



In the caudal vertebrae the transverse processes are more or 

 less aborted, while the neural spines and hajmal ones are often 

 conspicuously developed. In Sphcniscus demersus these spiu'-s 

 are bifid, and the htemal spines are found only upon the last 

 two or three vertebrae. 



According to Professor Watson, the number of vertebrae in 

 the spinal column never exceed 43 (Spheniscus demersus, S. magel- 

 lanicus, and S. meudiculiis), while in the majority of the species 

 there are but 42. 



In the skeleton of Eudyptes chrysocome we find the type of 

 the sternum as it usually occurs in this family of birds. Here 

 the bone is of an oblong form, well concaved upon its dorsal 

 aspect, while ventrad, a strong keel runs nearly its entire length, 

 and projects out considerably in front, especially in Aptcnodytcs 

 pennantii. 



Posteriorly, the xiphoidal portion of the sternum shows upon 

 either side an elongated notch of nearly uniform width. The 

 lateral processes thus formed curve towards the middle line as 

 they pass backwards, and are longer than the sternal body. The 

 mid-xiphoidal process is of considerable width and size, and 

 frequently is perforated by foramina. (These do not occur in 

 all Penguins, and in E. 'pachyrhynchus they are so large that 

 they are sometimes incomplete, thus forming notches.) The 

 ventral margins of the costal borders are much raised and sharp, 

 thus forming marked depressions for the pectoral muscles. Dis- 

 tinctly quadrilateral in outline, the costal processes are strong 

 and thick, and are directed forwards and outwards. The 

 anterior border between them is transverse, with a much 

 aborted manubrium in the middle line (a process much better 

 developed in S. demersus). 



The ' costal grooves ' are deep and of uniform width, each 

 terminating, laterally, in a distinct pitlet. 



According to Watson, " the articular depressions of the recep- 

 tion of the sternal ribs are six in number on either side in 

 every species, with the single exception of Pygosceles tceniatuSy 

 in which, in accordance with the fact that seven ribs articulate 

 ■^ According to Gervais and Alix in OsUologie et Myologie dcs Manchots. 



