194 



Annals of the Carnegie Museum. 



the adult one unbroken surface — a very smooth and firmly-ossified 

 tract. 



The outer angles of the gluteal ridges are rounded and project im- 

 mediately over the antitrochanter on either side, from which point 

 each ridge runs almost directly backwards to the hinder margin of the 

 bone. This latter, as a whole, is concave towards the posterior aspect, 

 and from its outer angles the curved and inturned pubic bones may be 

 seen pointing towards each other, their tips some two centimeters 

 apart. • 



Only a limited part of the surface of either ischium can be discerned 

 from this superior view, as these bones behind are nearly at right angles 

 with the overhanging ilia. 



Among all the ArdeincB that I have had the opportunity to e.xamine, 

 the post-acetabular surface is about equal in extent with the pre-ace- 

 tabular area. In the former the general surface is convex, while in the 

 latter it is concave ; the boundary between them I place, in common 

 with Owen, at the line of the gluteal ridge. The post-acetabular sur- 

 face slopes downwards from a line joining the outer gluteal angles ; 

 the amount of which declination can best be appreciated by a glance 

 at my figure of the side view of this pelvic bone (Fig. 14). 



Fu;. 28. Right lateral view of the skull of Nylicorax violarcus, "bird of the 

 year" (July). Natural size from a Louisiana specimen collected by the author. 



Upon lateral aspect the centra of the leading vertebrae may be seen 

 below the eaves of the iliac roof, and some idea gained of the mass- 

 iveness of the osseous column upon which the pelvis of this Heron is 

 built. 



The acetabulum is large and circular, with its floor more than usually 

 deficient, the inner ring nearly equalling in size the outer, while the 



