STUDIES IN MAMMALIAN EMBRYOLOGY. 481 



Studies in Mammalian Embryology. 



III.— The Placentation of the Shrew (Sorex 

 vulgaris, L.). 



By 



A. A. W. Iliibreclit, LL.D., C.M.X.S., 



Professor of Zoology in the University of Utrecht. 



With Plates 31 to 39. 



A. Introduction. 



As a sequel to my investigations on the placentation of the 

 hedgehog (' Quart. Journ. of Microscop. Science/ vol. xxx, 

 part 3, 1889) I was very anxious to collect a similar series of 

 data with respect to diflFerent genera of Insectivora, in order 

 to determine to what extent the development of the placenta 

 might be said to agree in various representatives of this 

 archaic order of Mammalia. It will be seen from the follow- 

 ing pages — as also from what I hope to publish ere long about 

 Indian Insectivora — that this agreement is very small indeed. 



The shrew was in the first place selected ^ as a type of com- 

 parison because the mole was then already being studied by 

 Professor Strahl, of Marburg, whose results with respect to 

 these questions have since been published in the ' Anatomische 

 Hefte ' von F. Merkel und R. Bonnet, ii, 1892. 



* A preliminary communication was made by me to the Academy of 

 Sciences at Amsterdam, at its meeting of 27th September, 1890, in which 

 the chief results, which are fully described at this paper, have already been 

 briefly noticed (vide vol. viii, p. 79, of the 'Verslagen en Mededeelingen van 

 de Koninkl. Akademie van Wetenschappen te Amsterdam '). 



VOL. 35, PART 4. — NEV7 SER. L L 



