20 THE DESCENT OF THE PRIMATES 



obviously impossible to place the Lemurs of the 

 Tertiary period anywhere on the line of ascent 

 of the Primates. The moment we have traced 

 the Primates as far as the earliest Tertiary they 

 can only be connected genetically to ancestors of 

 the Secondary period. And we are prevented 

 from assuming that these Mesozoic ancestors 

 were in any way Lemur-like, because both anat- 

 omy and embryology point most distinctly in 

 another direction, namely, in that of the Insec- 

 tivora. I would here remind you of Huxley's 

 verdict pronounced sixteen years ago, to which 

 I have already alluded, that among the Insec- 

 tivora, the spiny and the hairy hedge-hog (Erina- 

 ceus and Gymnura) represent the most central 

 type. Curiously enough, these two offer in their 

 embryonic development certain particulars with 

 which we can connect the divergences of the 

 Primates much more easily than with the Lem- 

 urine development. 



The formation of tlie human placenta, of the 

 human amnion, of the human decidua refiexa, is 

 foreshadowed in the hedgehog's development^ 

 in such a way as to strongly support the views 

 concerning the pedigree of the Primates here 



1 A. A. W. Hubreclit. The Placeutation of Eriiiaceus euro- 

 paeus ; Quarterly Journal of Microsc. Science, vol. xxx. 1 889. 



