AXIAL SKELETON OF THE PELECANTD^E. 329 



(though much narrowed transversely) the subcentral antero-posterior groove of the 

 lumbo-sacral vertebrae (Plate LIX. fig. 3). 



In these three vertebrae the parapophyses become again suddenly and greatly deve- 

 loped (especially those of the first sacral vertebra), abutting moreover against the ilium. 

 The three parapophyses of each side are united together distally. 



The diapophyses of these vertebrae take origin at a higher and higher level (i. e., 

 more and more dorsad) as we proceed postaxially, so that in the thirty-second vertebra 

 they simply diverge from the lateral margin of the summit of the neural arch. 



The coalesced neural spines of these and of the lumbo-sacral vertebra form a rounded 

 antero-posterior prominence, convex transversely, running along the middle of the 

 dorsum of the pelvis (Plate LIX. fig. 1). 



THE SACRO-CAUDAL VERTEBEJE. 



These are generally four ; but there may be only three 1 of these vertebrae. They are 

 differentiated from those of the last category by the non-union serially and distally of 

 their parapophyses together, or with the diapophyses of the sacral vertebrae. 



The THIRTY-THIED, THIETY-FOUETH, THIETY-FIFTH, and THIRTY-SIXTH VEETEBE^B form a 



series decreasing in size postaxiad, each provided with a parapophysial process (on each 

 side), which ascends postaxiad and dorsad to the ilium (Plate LIX. fig. 3). 



The diapophyses proceed externad from the dorsum of the neural lamina, while 

 the neural spines are ankylosed together antero-posteriorly as before. A foramen 

 is thus formed (apparent on the dorsum of the pelvis) between each serial pair of 

 diapophyses. 



As we proceed postaxially, however, the diapophyses spring successively from a 

 lower (less dorsad) level as regards the neural spines ; so that generally in the last 

 sacro-caudal they have again completely coalesced with the parapophyses ; and thus 

 the antero-posteriorly extended canal between the diapophysial and parapophysial 

 elements, which has hitherto existed right through the vertebral column from the 

 axis inclusive, here ends and is finally closed. 



THE CAUDAL VERTEBRAE. 







These vertebrae may be five 2 or six in number (more generally six) apart from the 

 terminal pygostyle (Plate LIX. fig. 6). 



1 As in the specimens Nos. 527 A and 67. 7. 8. 4 in the British Museum. 



2 I have only found five in the specimen lent me by Professor Garrod, and in a skeleton of P. mitratus 

 (No. 70. 3. 30. 1) in the British Museum. Thus in this individual (with but three lumbar vertebra;) there 

 are but forty vertebrae in all, apart from the pygostyle. In the specimens with only three sacro-caudals, there 

 were six free caudals, therefore forty-one vertebrae in all, apart from the pygostyle. 



