SHUFELDT : OSTEOLOGY OF THE STEGANOPODES 171 



costal ribs of this pair quite reach the sternum. On the left side in the specimen 

 before me there is also a "floating costal rib," with a length of nearly 3 centimeters. 

 It lies close along the posterior border of the distal moiety of the ultimate hsema- 

 pophysis. 



This last-mentioned bone in a specimen of P. urile articulates with the sternum 

 on the left side, and no doubt from time to time such will be found to be the case 

 in other species of Phalacrocorax, i. e. the ultimate pair of costal ribs or haema- 

 pophyses, upon one side or the other, or for the matter of that, upon both sides, may 

 join with the sternum the pelvic ribs to which they belong. 



In Phalacrocorax we find upelvis very much like the one we described for Anhinga. 

 The ilia are horizontally spread out in front, where they may be so thin as to present 

 a number of perforating foramina. In the'postacetabular region these bones come 

 much closer together, both actually and relatively, than they do in the Darters. The 

 interdiapophysial foramina also are present, a row upon either side of the posterior 

 sacral crista, and they are very large just before we arrive at the first caudal vertebra. 

 The internal iliac borders are not elevated here as they are in Anhinga. Cormorants 

 of this genus also have the large obturator space ; the enormous ischiadic foramen ; 

 the rudimentary propubis ; and the same peculiarities of the postpubis. 



Posteriorly, either ilium sends back a conspicuous process, and the two hold 

 firmly between them the first free caudal vertebra. In some species, as P. urile, 

 they may grasp two instead of one. An ilio-ischiadic notch is also present upon either 

 side of the pelvis. 



There seem to be seventeen vertebra? included in the pelvic sacrum to the fifteen 

 we found in Anhinga. Six of these are beneath the fore part of the ilia ; two more 

 with aborted processes lie immediately between the large acetabulae ; two true dorsal 

 ones follow these, and they have their lateral processes thrown out as abutments to 

 the walls of the pelvis; finally seven more so-called uro-sacrals are to be counted 

 between these and the first caudal. 



Viewed ventralwise, the pelvic basin is seen to be deep and capacious. Another 

 marked character on this aspect is the strong 'ridge or crest of bone on either side, 

 which extends longitudinally backwards from a point below the cotyloid ring to the 

 hindermost angle of the ischium. It is strongest directly below the great ischiadic 

 foramen. This character is but feebly marked in the pelves of the Darters. 



There are six caudal vertebrae and a pygostyle. The latter is large ; pointed 

 posteriorly, triangular in form, broad and flattened at its lower part behind, in 

 front of which there is a haemal spine. Haemal spines are also found upon the last 

 three caudals, and neural ones on them all. These tail vertebrae are large and strong, 



