166 A. A. W. HUBRECHT. 
p. 403) giving his reader the impression that the value of 
the deciduate and non-deciduate type of placenta has been 
overrated. Not only that, but since then among the so-called 
deciduate placentary mammals some have been detected 
(Hubrecht, Hill) in which the placenta instead of being 
deciduate might even be termed contra-deciduate, in this 
sense that no maternal tissue is being expelled after parturi- 
tion, but that embryonic tissue is undergoing a process of 
resorption on the part of the mother. 
And so I will not deny that the value which we ascribe to 
particular points in the placentation and in the puerperium 
of mammals may vary according to the greater or lesser 
acquaintance we possess of their details. But I cannot over- 
look that even Flower and Lydekker in the same citation 
maintain that “the characters and arrangements of the feetal 
structures . . . will form, especially when more completely 
understood, valuable aids in the study of the natural 
affinities and evolution of the mammalia.” 
On p. 159 I have developed the idea that in certain cases 
the ‘‘ character and the arrangement of the foetal structures ” 
will even prove to be a discriminating re-agent both delicate 
and powerful. And I must emphatically repeat that the case 
of the ordinal separation of the Lemurs from the Primates is 
one of crucial importance, and that, whatever inconvenience 
may in the present state of our knowledge be caused by it 
to paleontologists, we should on no account surrender or 
acquiesce to the proposal of so eminent an authority as 
Wortman, but should determine (1) to keep separated the 
two orders of the Primates and the Lemures, and (2) to use 
all our ingenuity and acuteness in order to trace, as new 
fossil remains come to light, remains belonging to the one 
and to the other order by osteological details ‘only. But 
then of course such finds which bring us teeth or even teeth 
and skulls only, may in some cases be misleading, and only 
complete skeletons can have full demonstrative weight. 
This new and more exacting method of dealing with fossil 
remains is in the nature of things in the first place applicable 
