1882.] DR. VAN DYCK ON SYRtAN STREET-DOGS. 367 



of the alimentary organs, but in other respects, as their defensive 

 armature, remarkably specialized. 



The two Old- World forms ManidcB and OrycteropidcB are so 

 essentially distinct from all the American families, that it may even 

 be considered doubtful whether they are derived from the same 

 primary branch of mammals, or whether they may not be offsets 

 from some other branch, the remaining members of which have been 

 lost to knowledge. 



Alphonse Milne-Edwards, in discussing the inferences to he derived 

 from the study of the foetal membranes of the Edentates^ has maintained 

 that one of two views must be accepted : — either that it shows that 

 no value can be attached to the placentation in seeking natural affinities; 

 or that the Edentates as we know them now are not a homogeneous 

 order, but should be separatedinto several distinct natural groups. It 

 is the latter view to which he gives the preference. It need scarcely 

 be remarked that the observations made in the present communi- 

 cation lead to a similar conclusion. 



2. Ou the Modification of a Race of Syrian Street-Dogs by 

 means of Sexual Selection. By Dr. Van Dyck. With 

 a Preliminary Notice by Charles Daewix, F.R.S., 

 F.Z.S. 



[Eeceived April 4, 1882.] 



Most of the naturalists who admit that natural selection has been 

 effective in the formation of species, likewise admit that the weapons 

 of male animals are the result of sexual selection — that is, of the best- 

 armed males obtaining most females and transmitting their masculine 

 superiority to their male offspring. But many naturalists doubt, or 

 deny, that female animals ever exert any choice, so as to select certain 

 males in preference to others. It would, however, be more correct 

 to speak of the females as being excited or attracted in an especial 

 degree by the appearance, voice, &c. of certain males, rather than of 

 deliberately selecting them. I may perhaps be here permitted to 

 say that, after having carefully weighed to the best of my ability the 

 various arguments which have been advanced against the principle of 

 sexual selection, I remain firmly convinced of its truth. It is, how- 

 ever, probable that I may have extended it too far, as, for instance, 

 in the case of the strangely formed horns and mandibles of male 

 Lamellicorn beetles, which have recently been discussed with much 

 knowledge by W. von Reichenau', and about which I have always felt 

 some doubts. On the other hand, the explanation of the development 

 of the horns offered by this entomologist does not seem to me at all 

 satisfactory. 



1 Annale3 des Sciences Naturelles, Zoologie, 6me serie, tome viii. p. 6 (1879). 

 ^ " Uebei- den Ursprnng dcr secundiircn luilnnlielien Geschlechtscharakleren 

 &c.,'' Kosnjos, Jahrgang v. 1881, p. 172. 



Proc. Zool. Soc— -1882, No. XXV. 25 



