AXIAL SKELETON OF THE PELECANID^. 341 



however (as in No. 1186 d in the College of Surgeons' Museum), there are four lumbar 

 vertebrae and three presacral foramina. The more postaxial foramen also is smaller 

 compared with its serial predecessor than is the most postaxial one of Pelecanus. 



The Lumbo-saceal Vektebile. 

 These are generally three in number (normally the twenty-eighth, twenty-ninth, 

 and thirtieth), and resemble those of Pelecanus in most of their characters. Some- 

 times there are but two such vertebrae. 



The Sacral Vertebra. 

 These are but one or two^ in number (from the thirtieth, the thirty-first and 

 thirty-second vertebrae) ; and, unlike Pelecanus, the parapophysis of the second (when 

 there are two) may be longer and much stronger than that of the first. Their diapo- 

 physes arise at a very high (dorsal) level. 



The Sacro-Caudal Vertebra. 



They are from four to sLx in number, including the thirty-third, thirty-fourth, 

 thirty-fifth, thirty-sixth, and thirty-seventh vertebra (Plate LX. fig. 3). 



They difier strikingly from those of Pelecanus in that they have their parapophyses 

 quite suddenly bent up, so that they are as much difierentiated off from the sacral 

 vertebrse as are the lumbo-sacrals in front ; and there is consequently a fossa on each 

 side behind the sacral parapophyses. The parapophyses gradually descend postaxially, 

 conjoined with the diapophyses, and being more and more inclined postaxiad. 



The last three interparapophysial spaces open widely on the dorsum of the pelvis. 



The Caudal Vertebrae. 



These are seven ^, apart from the pygostyle, in number. Unlike those oi Pelecanus 

 they increase in breadth considerably and gradually postaxiad. 



A hypapophysis does not appear till the fifth or sixth, and it is longer on the 

 seventh. 



The transverse processes are longest in the sixth caudal vertebra. The pygostyle is 

 long, prismatic, with a sharp dorsal ridge ; it is ventraUy flattened ; and its ventral 

 margin is veiy slightly concave (Plate LIX. fig. 7). 



The Pelvis. 



This complex structure, including fifteen vertebrae in its extended ankyloses, pretty 

 closely resembles the pelvis of Pelecanus (Plate LX. figs. 1-3). 



Laterally viewed, however, the opening of the acetabulum is smaller, the sacro-sciatic 

 foramen is longer, the obturator-foramen narrower, and the pubis more postaxially 

 extended (Plate LX. fig. 2). 



• Very rarely three, as in No. 527 h in the British Museum. 

 ^ There are eight in No. 527 b in the British Museum. 



3a2 



