AXIAL SKELETON OF THE PELECANID^. 363 



Seen ventrally, the ilia extend out as in Phalacrocorax ; and there are three presacral 

 foramina (s^, 5^, s^) on each side. The lateral acetabular fossae {f) are notably different 

 from those of Phalacrocorax, owing to the encroachment inwards of the margins of 

 the acetabula, which almost reduce the preaxial part of each fossa to a narrow chink 

 (Plate LXI. fig. 8). 



The ridge running postaxiad inside the ischium is less marked ; and there is no such 

 expanse of ilio-ischial surface dorsad of the postaxial part of such ridge as there is in 

 all the other three genera, above all in Pelecanus. On the other hand, the expanse of 

 the ischial surface ventrad of the postaxial part of such ridge is greater relatively than 

 even in Phalacrocorax, and therefore very much greater than in Sula or Pelecanus. 

 The pubes do not approximate ventrad as in Phalacrocorax or Sala. 



Thk Ilium. 



The process {st) described as existing in Phalacrocorax a little postaxial to the antitro- 

 chanteric process also exists here, but is nearer to the last-njentioned process. This 

 more postaxial process may be called the posttrochanteric process (Plate LXI. fig. 7). 



Besides the points above noted, a ridge runs mediad and preaxiad from this post- 

 trochanteric process, and joins its fellow of the opposite side in the median antero- 

 posterior iliac ridge. Another ridge {Ir), very much stronger indeed, runs postaxiad from 

 the same process, forming the very prominent ridge of the postacetabular part of the 

 ilium, before noticed. This ridge causes each postacetabular ilium to present three 

 surfaces, one externad, one dorso-mediad, and the other ventro-mediad; and the pro- 

 minent ridge in question divides the externad from the dorso-mediad surface. 



The ilio-pectineal prominence [Ijp) is more sharp and prominent than in any other form 

 of Pelecanidse. 



The Pubis. 



This is but a very feeble ossification, and unites with the ischium for a longer space 

 than in the other Pelecanidse. 



The Ischium. 



This bone differs from that of the other Pelecanidse by its greater postaxial expansion 

 dorso-ventrally, presenting an extensive grooved surface (fig. 8, g) ventrally, as already 

 noted in describing the ventral aspect of the pelvis. 



The Ribs. 

 There are seven or eight vertebral and six sternal ribs. 



The Vebtebral Ribs. 



The first two belong to the cervico-dorsalvertebrse, and have no corresponding sternal ribs. 



The second may or may not have an unciform process ; and the same is the case with 

 the seventh rib. The eighth, when present, has no such process. 



The last rib has no tubercular process. 

 VOL. X. — PART VII, No. 7. — August 1st, 1878. 3 d 



