The Development of the Mole (Talpa Europea). 



STAGES E TO J. 



By 



Walter Heape, M.A., 



Resident Superintendent of tlie Plymouth Laboratory of the Marine Biological 

 Association of the United Kingdom. 



With Plates XIII, XIV, and XV. 



During the preparation of the following paper I have been 

 conscious that a considerable proportion of the matter included 

 is of little special interest ; at the same time it has appeared 

 to me that the course of the development of certain organs in 

 the Mole deserves to be recorded, and in order to do so satis- 

 factorily I have been compelled- to mention much vrhich is not 

 different from embryological phenomena already observed in 

 other Vertebrates. 



I have further been led to hope that a somewhat complete 

 account of the development of one of the Insectivora will not 

 be without value. 



To facilitate reference I have described the development of 

 the embryo in stages, which, in continuance with the stages of 

 growth described in a former paper (No. 8), will be called 

 Stages E, F, G, H, and j. A summary of the various sections of 

 this paper will be found on p. 132. 



External Features. 



Stage E. — The youngest embryo which I have figured (fig. 1) 

 lies flat upon the surface of the blastodermic vesicle. The 

 embryo is '76 mm. long, and is narrow in the centre and wider 



9 



