THE SKELETON. 65 
obturator foramen. The pubis is the ventral portion, pos- 
sessing two rami, one projecting laterad to unite with the 
ilium, cotyloid, and ischium, and the other projecting 
caudad along the mid-ventral line, joining its fellow and 
the ischium. In young kittens the junction of these parts 
is plainly visible, but in adult specimens it is wholly oblit- 
erated. In old specimens the ischium and pubis become 
more or less anchylosed with their fellows in the mid- 
ventral line. The cranial and dorsal border of the ilium is 
the crest (Fig. 39). The rough crescentic area on the 
‘medial aspect is the auricular surface for articulation with 
the sacrum. The cranial rounded angle of the crest is the 
anterior superior spine. The anterior inferior spine is the 
small prominence craniad from the ventral termination of 
the auricular surface. 
The ischium presents a spine on its dorsal border near 
the acetabulum. Between this spine and the posterior in- 
ferior spine of the ilium, is a shallow concavity termed the 
greater sciatic notch in distinction to the lesser sciatic notch 
between the spine of the ischium and the tuberosity. The 
acetabulum or cotyloid cavity forms the cup for the articu- 
lation of the femur. The interruption in its ventral border 
is the cotyloid notch, at whose base there is a depression for 
the attachment of the ligamentum teres holding the femur 
in place. The junction of the pubis with its fellow is known 
as the symphysis. The cranial portion of the bone lying 
on either side of this is called the body, the caudal part 
taking the name of ramus. The latter forms part of the 
boundary of the obturator foramen and meets the ramus of 
the ischium. This foramen gives passage to the obturator 
nerve and vessels. 
In the Sirenia, which have no pelvic limbs, the innomi- 
nate bones are rudimentary. In the Cetacea these bones 
are also rudimentary, which fact indicates that the ances- 
tors of these forms possessed functional hind-limbs. 
