344 PEOF. ST. GEOEGE MIVAET ON THE 



The fifth rib has nouncinate process 1 ; the flattening and expansion are less and more 

 dorsad ; and the tuberculum is reduced to a rudiment. 



The sixth and seventh ribs have no unciform process, and no tuberculum whatever. 

 They end proximally in a very slender pointed process, which abuts against the end of 

 the supporting transverse process on the ventral aspect of the ilium. 



THE STEKNAL RIBS (Plate LX. fig. 4) 



are all long and slender, and differ much in shape from those of Pelecanus. They 

 increase in length postaxiad to the fifth and sixth. 



The first five expand distally and transversely somewhat, to be implanted in the 

 pleurosteon. The sixth and last is not expanded distally, but presents a small articular 

 facet at its distal end. 



The fifth is slightly more than twice the length of the first. 



The first and second together about equal the length of the fifth. The last two may 

 be grooved externally. 



Sometimes 2 there is a seventh sternal rib, which unites distally with the sixth, and 

 has no ossified vertebral rib to it. 



THE STERNUM (Plate LX. figs. 4 & 5) 



is relatively much longer and narrower than in Pelecanus. Its keel stretches more 

 preaxiad relatively. 



The coracoid grooves (c) together form a more acute angle. 



The median xiphoid is rounded, or may be slightly emarginate (mx}. Each lateral 

 xiphoid (Ix) is somewhat spatulate. The sternum is not generally ankylosed to the 

 clavicles. 



The pleurosteon is, again, very much narrower dorso-ventrally than in Pelecanus. It 

 presents six articular surfaces (the last very indistinct), separated by five fossae. 



The ventral surface of the sternum is less convex, and its dorsal surface less concave, 

 than in Pelecanus, especially in its ventral half. 



Its total length is nearly three times its breadth 3 , measured transversely at the post 

 axial end of keel. 



The coracoid grooves are hardly separated medianly. 



The costal angles (ca) are less concave on their ventral surface, and are less pointed 

 at their ends. 



PHALACROCORAX. 



The skeleton of this form is figured, under the title " Graculus," by Mr. Eyton in his 

 'Osteologia Avium,' plate 5 L; and a few words respecting it are to be found at p. 218. 



1 Except as above. 2 E. g. in Nos. 1168, B and c, in the College of Surgeons' Museum. 



* Not always so much, e. g. in 731 A in the British Museum. 



