300 



OSTEOLOGY OP TUBINARES AND STEGANOPODES. 



concave and sharp, while above this, again, there is a compressed proc- 

 ess thai represents the manubrium. 

 The lover border of the keel is straight and in the horizontal plane, 



being capped off with a spreading rim. 



This bolder merges into the surface of the 

 body of the bone before it half way readies 

 the xiphoidal notch. 



The sides of the keel are smooth, and 

 neither it nor the under side of .the sternal 

 body show, in this specimen, any of the 

 muscular lines usually present in most 

 birds. 



A broad median notch, concave from 

 side to side, convex from before backward, 

 lies between the lofty superior portions of 

 the coracoidal grooves. These latter meet 

 in front of it at the manubrial base, while 

 behind its surface becomes directly contin- 

 uous with the general surface of the upper 

 side of the body, and right where the group 

 of pneumatic foramina are found. 



A coracoidal groove looks forward and 

 outward for its upper portion, directly up- 

 ward for its lower, and extends about half 

 way between the base of the costal process 

 and the manubrium. It consists of two 

 portions which are directly continuous with 

 each other. The lower one is a shelf-like 

 projection, with a convex border forward 

 and its articular surface in the horizontal 

 plane. Immediately above this rises a 

 much broader surface, though not so long, 

 which is decidedly convex from above 

 downward. This portion of the facet for 

 the coracoid is considerably higher than 

 the plane in which the borders of the body 

 of the bone are found. It faces forward 

 and outward, and has one regular convexity 

 as its limiting margin above. 



Between the point of its outer termina- 

 tion and the apex of the corresponding- 

 cost al process the border is one sweeping 

 concavity. 



This form of sternum seems to be pecu- 



Fig.30. •■ : ]jar to the Sulidce, and it differs in a nuin- 



lofi lateral ize. By the i n • , i ,■• « ,-, ,^ . 1 



,, berot points both from the Cormorants and 



author, ii in (In- »n me specimen as l 



Bhown in Figs. 24 et froin the Pelicans. Nor do we see any- 



