124 
THE DESCENT OF MAN. 
'Part I. 
grow into two distinct uteri, each, with a well-constructed 
orifice and passage, and each furnished with numerous 
muscles, nerves, glands and vessels, if they had not 
formerly passed through a similar course of develop- 
ment, as in the case of existing marsupials. No one will 
pretend that so perfect a structure as the abnormal 
double uterus in woman could be the result of mere 
chance. But the principle of reversion, by which long- 
lost dormant structures are called back into existence, 
might serve as the guide for the full development of 
the organ, even after the lapse of an enormous interval 
of time. 
Professor Canestrini , 36 after discussing the foregoing 
and various analogous cases, arrives at the same con- 
clusion as that just given. He adduces, as another 
instance, the malar bone, which, in some of the Quad- 
rumana and other mammals, normally consists of two 
portions. This is its condition in the two-months-old 
human foetus ; and thus it sometimes remains, through 
arrested development, in man when adult, more especially 
in the lower prognathous races. Hence Canestrini con- 
cludes that some ancient progenitor of man must have 
possessed this bone normally divided into two portions, 
which subsequently became fused together. In man 
the frontal bone consists of a single piece, but in the 
embryo and in children, and in almost all the lower 
mammals, it consists of two pieces separated by a dis- 
tinct suture. This suture occasionally persists, more 
or less distinctly, in man after maturity, and more fre- 
36 ‘Annuario della Soc. dei Naturalisti in Modena,’ 1867, p. 83. 
Prof. Canestrini gives extracts on this subject from various authorities. 
Laurillard remarks, that as he has found a complete similarity in the 
form, proportions, and connexion of the two malar bones in several 
human subjects and in certain apes, he cannot consider this disposition 
of the parts as simply accidental. 
