18B&] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 303 



perior boundary to a long, narrow, obturator space, which opens freely 

 into the rather small obturator foramen. 



A pro-pubis does not develop in this Gannet, while the post-pubisis 

 for the most of its extent fragile and slender. It begins to increase in 



Fig. 31. Tclvis of Svla bassana, with sacral rib; left lateral view; life size. By the author, from Uie 

 same specimen as shown in Fig. 24 et seq. 



size just before arriving at a point opposite the end of the ischium. At 

 this point it offers a small facet on its upper margin for the ischiac. 

 postero- inferior angle, and the two bones are in contact during life 



