SKELETON OF PHORORHACOS INFLATUS. 73 
regarded as lumbar; the last of these bears a broad parapophysial process which abuts 
against the inner border of the ilium. Behind this there seem to be two or three 
lumbo-sacrals (M/ivart) in which no parapophyses are present and, except perhaps on 
the hindermost, no diapophyses, unless these are directed dorsad. In this region the 
pelvis is very narrow, so that the lateral acetabular or anterior renal fossee are extremely 
small. 
Behind the lumbo-sacrals are the true sacrals, two in number. Both these possess 
ventral processes, which, no doubt, are formed by parapophyses + sacral ribs. In the 
first the process is stout, much expanded at its outer end, and directed outward, upward, 
and somewhat forward. In the second this process is very slender and quickly fuses 
with the middle of the upper process (diapophysis), which in this vertebra is stout and 
directed outward and forward. The diapophysis of the anterior sacral is slightly 
in front of, and about 1 cm. above, the parapophysis; it is directed backward, outward, 
and upward. The two diapophyses are separated by a nearly circular space, and their 
expanded outer ends, together with that of the ventral process of the anterior sacral 
fuse into a common mass of bone, which abuts against and fuses with the inner surface 
of the ilium immediately behind the acetabulum. 
On the vertebral centra, at the level of the second sacral rib, there is a median 
hemal ridge, which is continuous as far as the third of the urosacrals which bear 
transverse processes. ; 
Behind the last sacral there is an interval in which no transverse processes are 
present: then they reappear, the first being very slender and directed backward at a 
very acute angle with the vertebral column ; at its distal end it fuses with the succeeding 
process. ‘This also is directed backward, but is much stouter than the last and greatly 
expanded at its distal end, where it abuts against the inflected portion of the ilinm 
forming the floor of the pocket-like renal fossa. The next transverse process is very 
broad, and likewise unites externally with the ilium ; it is separated from the processes 
in front of and behind it by oval foramina. Behind this there are four pairs of similar 
processes borne by vertebree with long, narrow centra having a slight hemal ridge. The 
free end of the last fused centrum is flat or slightly convex. On the dorsal surface the 
neural spines of the postacetabular “ sacrals” form a prominent median ridge, separated 
from the ilia, anteriorly at least, by a narrow groove; posteriorly there are several pairs 
of slit-like interosseous foramina. 
The pelvis, seen from above (Plate XVI. fig. 1), appears very long and narrow, the 
postacetabular region not being expanded to any great extent. Along the middle 
line runs a prominent ridge, formed in front by the fused upper edges of the ilia and 
behind by the united neural spines of the postacetabular vertebre. Opposite the 
hinder border of the acetabulum is a transverse ridge which, at its outer ends, rises 
into a pair of very prominent supra-trochanteric crests; these, with the anti-trochanters, 
form prominent lateral projections. On each side of the median ridge in the post- 
acetabular region there is a narrow groove separating it from the upper edges of the 
M 2 
