189^.] OSTEOLOGY OF BIEDS. 89 



the free ventral border of the carina of the sternum is peculiar in 

 that its edge becomes suddenly transformed from a broad to a 

 sharp one, as though it had been shaved off on either side by a 

 knife (see figs. 1, p. 87, & 2, p. 88). The posterior end of the 

 corpus sterni is doubly notched. 



The sternum of Fregata is unique in that the furcula is 

 ankylosed dorsally with the acrocoracoid, and ventrally with the 

 carina sterni. 



As will be seen by the " key," there are three types of pelvis — 

 that of Phaeihon and Fregata constituting one, that of Pelecmius a 

 second, and those of Plialacrocorax and Sulci a third. This last 

 must be regarded as the typical Steganopodous pelvis (fig. 3, p. 88). 



The pelvis of Pelecanus, resembles somewhat closely that of 

 Sula, and after this, that of the Anseres ; but differs in the greater 

 width of the preilium, and in that the postilium is not laterally 

 expanded and truncated posteriorly as in the latter group. 



The pelvis of Phaeihon (fig. 4, p. 89) and of Fregata closely 

 resemble one another, and both differ much from that of any other 

 Steganopod. That of Phaeihon most nearly resembles that of Mo- 



Fig.4. 



Dorsal aspect of the pelvis of Phaethm fiavirostris (nestling). 4 nat. size. 



n.. Ilium ; Syn.s.v., Synsacral vertebrae ; Syn.f., Synsacral foramen ; 

 P., Pubis ; Is., Ischium. 



imtus, but differs therefrom in that the postacetabular ilium is much 

 flattened and bent downwards and outwards, in that the ischium is 

 much longer than broad, instead of being nearly as broad as long, 

 and in the greater length of the pubis. This resemblance can 

 scarcel}' be regarded as other than an accidental one. What is 



