SKELETON. IIt 
the ilium is very long and the ischio-pubis is strongly compressed, 
obturator foramen and ischio-pubic fenestra being absent. 
Omitting the extinct rhynchocephals, whose pelvis resembles that of 
the stegocephals, the reptiles have the pelvic bones more solid and dis- 
tinct than do the ichthyopsida; the ilium is strong, with its dorsal end 
frequently expanded; the ischio-pubic fenestra is large; and ischium 
and pubis are united to their fellows directly, or by the intervention of 
the epipubic cartilage, or its modification, the ligamentum medium 
pelvis. Asa rule all three bones meet in the acetabulum and there 
are large prepubic processes, though these are small in the lizards and 
are lacking in crocodiles. 
Fic. 116. Fic. 117. 
Fic. 116.—Pelvis of snapping turtle (Chelydra) from below. e, epipubis; f, femur; 
h, hypoischium; /, ligamentum medium pelvis; p, pubis; pp, pectineal process. 
Fic. 117.—Pelvis of Iguana tuberculata, after Blanchard. a, acetabulum; e, epipubic 
cartilage; f, femur; i, ilium; is, ischium; of, obturator foramen; ~, pubis; p, prepubis; 
s,! s?, first and second sacral vertebra. 
Many theriomorphs have the pelvic bones fused much as in mam- 
mals. In Sphenodon and turtles the epipubic cartilage bounds the 
fenestra on the median side, and Sphenodon and the plesiosaurs have 
a separate obturator foramen, but the two are merged in the chelonians. 
Most lizards have slender pubic bones, perforated by the foramen, and 
the part of the epipubis between the fenestre reduced to a ligament, 
while the posterior part of this, behind the ischium, may ossify as a 
distinct bone (os cloace or hypoischium). In the footless lizards the 
pelvis is reduced, being represented in the amphisbenans by rudiments 
of ischium and pubis, while all traces of the pelvis are lost in snakes, 
except the boas and some opoterodonts. The obturator foramen is 
very large in the crocodiles, the result of the oblique position of the 
