THE DESCENT OF THE PRIMATES 13 



liave only become acquainted in the past few 

 years.^ This divergence concerns the mode of 

 attachment of the unborn animal to its mother 

 during the period of foetal life. 



Lemurs from Madagascar and Lemurs from 

 India are found to be enveloped while inside 

 their mother's womb in a closed sac that carries 

 all over its outer surface an immense number of 

 small knobs and excrescences. If we would make 

 a comparison with a texture perhaps more famil- 

 iar to you we might say that the outer surface 

 of this sac, which entirely hides the young ani- 

 mal from our view, resembles Astrakhan fur. In 

 technical language it is called " villiferous." The 

 numerous separate little knobs, or villi, carry 

 extremely fine blood-vessels that directly com- 

 municate with the embryo's vascular system. 

 In this way the whole of the outer surface of 

 the sac may be considered as being eminently 

 fit for respiratory function or for nutritive ab- 

 sorption. The latter functions are actually in- 

 cumbent upon this villiferous surface, which fits 

 beautifully into corresponding little cavities by 

 which the internal surface of the maternal womb 

 is honey-combed. These two surfaces, the ma- 



1 A. A. W. Hubrecht, Spolia Xemoris ; Quarterly Journal 

 of Microscopical Science, vol. xxxvi.,p. 77. 



