C. W. And reus — ^pyoi'nis from Madagascar. 247 



pneumatic fossas, which are separated only by a thin horizontal 

 plate of bone. In the second pelvic the top of the neural spine 

 is completely fused with the ilia, as also are those of the other 

 preacetabular vertebrae, thus forming a high iliac crest, which is 

 convex from before backward. The second vertebra also has only 

 the diajDophysis developed, and bears a free rib ; there is in this case 

 a well-marked blunt hypapophysis. In the third the costal element 

 is fused with both the diapophysis and parapophysis, and forms 

 a pointed process projecting below the ventral margin of the ilium. 

 The next three vertebra have double transverse processes. As far 

 back as this point (i.e., to the hinder border of the sixth pelvic 

 vertebra) the ventral surface of the sacrum is convex from side to 

 side, and its long axis is nearlj'^ straight, but behind this it becomes 

 concave from side to side and strongly convex from before back- 

 ward, and opposite the origin of the free portion of the ischium 

 it turns sharpl}'^ dorsad and then again runs backward nearly in 

 a straight line, sloping somewhat upwards. The ventral convexity 

 occurs at the level of the acetabulum, and the vertebrge of this region 

 are fused into a solid mass, the only traces of the compound origin 

 of which are a few small foramina, which mark the intervals 

 between the parapophyses, the outer ends of which are completely 

 co-ossified with the pubes and ischia, with the ventral surface of 

 which the ventral surface of the sacrum forms a continuous curve. 



The pelvic vertebrae posterior to the convexity are six or seven 

 in number. They bear broad, thin, transverse processes, of which 

 the two or three anterior ones slightly overlap one another, and 

 the outer ends expand and unite closely with the thickened inner 

 border of the ilia. The ventral surface of the centra of the 

 anterior ones is convex from side to side, but that of the posterior 

 is flat or even slightly concave. In these posterior vertebrae the 

 transverse processes and the neural spine form a continuous nearly 

 semicircular plate of bone, which is convex in front and concave 

 behind, and the outer edge of which unites firmly with the ilia. 

 The anterior free caudals are similar in structure ; their centra are 

 procoelous and perforated ventrally by a pair of pneumatic foramina : 

 a pair of foramina also penetrate the base of the transverse process. 

 In the more posterior caudals the massive neural spine and trans- 

 verse processes are not united into a common plate of bone, and 

 the ventral pneumatic foramina are wanting ; their centra are 

 deeply cupped in front. 



In the pelvis the preacetabular portions of the ilia are inclined 

 to one another at a very acute angle ; as already mentioned, they 

 fuse along their dorsal margin with the tops of the neural spines of 

 the anterior pelvic vertebra, thus forming a high massive iliac 

 crest, convex from before backward. At about the level of the 

 acetabulum the ilia begin to diverge and are divided by a prominent 

 angular ridge into a superior surface, which together with the 

 broad united upper ends of the neural spines forms a wide pelvic 

 escutcheon, and a lateral surface which is nearly vertical. The 

 pelvic escutcheon is convex from side to side and is constituted 



