. Elements of Comparative Anatomy. 486 COMPAEATIVE Fig. 271. "View o£ the left side of a Bird's pelvis. The dotted portion represents that part of the thi-ee pieces of the pelvis, wliich extends backwards by the development of cartilage. The dotted line marks off that portion of the ilium (66) which grows forwards without the addition of any cartilage. The letters as in the preceding figures. of t]ie acetabulum, takes the same course; its ends project farther back than those of the ischium^ and generally converge; in Struthio they even form a symphy- sis. There are various kinds
. Elements of Comparative Anatomy. 486 COMPAEATIVE Fig. 271. "View o£ the left side of a Bird's pelvis. The dotted portion represents that part of the thi-ee pieces of the pelvis, wliich extends backwards by the development of cartilage. The dotted line marks off that portion of the ilium (66) which grows forwards without the addition of any cartilage. The letters as in the preceding figures. of t]ie acetabulum, takes the same course; its ends project farther back than those of the ischium^ and generally converge; in Struthio they even form a symphy- sis. There are various kinds of connections between the ilium and ischium, and between these and the pubis. The pelvis in the Mammalia is very dif- ferent. The primi- tive connection with the sacrum is always in front of the acetabulum. The ilium, however, is directed from be- fore backwards, and the hinder edge of the Bird's ilium corresponds to the antei-ior edge of the Mammal's ilium. Two different positions therefore for the ilium are derived from the Amphibia. In the Amphibia it is directed laterally and inferiorly away from its connection with the sacrum, in Reptilia and Aves obliquely forwards, and in Mammalia obliquely back- wards. The ventral portion of the pelvis encloses an obturator foramen, and is united ven- trally with that of the other side. The primitive pelvic carti- lage gives rise to the ilium and ischium; the pubis is derived from a separate rudiment, which is united with the ischio-iliac rudiment in the acetabulum (Man). This leads us to think that the pubis is an independent piece of the skeleton, which has retained its independence in the Cro- codilini. The ilium of the Mammalia is connected with a few vertebrae. The ischium also may be united with the false sacral vertebrte (Dasy- pus, Brady pus). When the two ventral pieces are united at the ischio-pubic symphysis, as they are in the Marsupialia, many Rodents, Ax'tiodactyla, and Peris- sodactyla, the pelvis is elongated in form.
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Keywords: ., bo, bookcentury1800, bookdecade1870, bookpublisherlondonmacmillan
