218 EDWARD B. POULTON. 



The Structures connected with the 0\rarian 

 Ovum of Marsupialia and Monotremata. 



By 



Ed^vard B. Poulton, IH.A*, 



of Jesus and Keble Colleges, Oxford. 



With Plate V. 



The Ovary of Marsupialia. — In the spring of 1883^ I 

 obtained an adult living female of Phalangista (P. Vulpina). 

 Although I have only been able at present to work upon the 

 ovaries of this Marsupial, I have no doubt that, in essential 

 points — such as the structure of the ripe Graafian follicle — the 

 present description will prove to be characteristic of the order. 

 It is very difl&cult to imagine such important characters to be 

 of less than ordinal value, especially when we consider that the 

 structure, hitherto described as the normal mammalian Graafian 

 follicle, appears to be practically constant in so many orders. 

 I have not, therefore, hesitated to give the above title to this 

 paper, although I hope to bring a posteriori proof when I 

 can find time and material. There are also certain points in 

 this ovary which I hope to further elucidate by more prolonged 

 investigation. 



The ovaries were hardened in chromic acid (of which the 

 strength was increased during the process), and afterwards 

 gradually in spirit. They were about 9 mm. in length, 6 mm. 

 in width, and 7 mm. in thickness. Their surface was studded 

 with large projecting follicles (see fig. 1 x 9). In nearly all 

 cases the sections were cut after staining the tissue as a wliole^ 



