THE FCETAL MEMBRANES OP THE VETiTECUATKS. 177 



The Foetal Membranes of the Vertebrates. 



An Address reprinted from the ''Proceedings of the 



Seventh International Zoological Congress " 



HELD at Boston, 1907.' 



By 

 A. A. W. llnbreclit. 



I WAS honoured by the request of the Executive Committee 

 to give an address at the first meeting' of the Embrj^ological 

 Section of the Seventh International Zoological Congress. 



I hope that in choosing for my subject the present state of 

 our knowledge concerning the fcBtal membranes of vertebrates 

 I can avoid the disadvantages of too much special detail, and 

 can at the same time call your attention to the fact that these 

 foetal membranes offer a very wide field for theoretical specu- 

 lation, that may in its turn influence our views concerning 

 certain important phylogenetic problems. 



The foetal membranes of vertebrates are known to occur in 

 reptiles, birds, and mammals. The enibryological hand-books 

 tell us that they are absent in amphibians and fishes. 



In consequence, a primary subdivision of the vertebrates 

 has been instituted, those with foetal membranes being classed 

 as Amniotaallantoidea, those without them as Anamnia anal- 

 lantoidea. From this nomenclature any close observer, even 

 when he is not a zoologist, may safely conclude that one of 

 the foetal membranes carries the name of amnion, the other 



1 At Professor Hubreclit's request this address is here reprinted. It 

 will assist readers in apprehending the conclusions which Professor 

 Hubrecht holds to be rendered probable by the large memoir published 

 in this Journal in November, 1908. 



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