22,8* ProF. T. Thomson Flyiin on Reproductive 



pregnant, and in each there were two well-advaiiced embryos. 

 A sketch of the pouch, drawn to scale, is shown in the 

 accompanying text-figure. The pouch has enlarged, and the 

 mammary glands have undergone tlie usual developn>ent 

 associated with pregnancy. There is, however, a conspicuous 

 difference between the anterior pair and the posterior pair in 

 this regard, the latter showing much greater development 

 than the former. Further, while the teats of the posterior 

 pair are quite normal, those of the anterior are extremely 

 small, re-entrant, and sunk into depressions, so that it would 

 be quite impossible that they could be used in lactatory 

 processes. This is the normal condition for the pregnant 

 female of Pseudochirus cookl at this stage. 



In the "further development towards the accommodation of 



Pouch of Pseudochi ins cooki at a fairly advanced condition of pregnancy. 

 Tlie unshaded elliptical area in centre represents the mouth of 

 the pouch. At a larer stage the pouch hecomes produced 

 forward on each side into a '' lateral pouch " as shown. 



the pouch-foetuses the posterior pair alone remains functional, 

 while the anterior glands undergo regressive changes. In a 

 female with pouch-young the anterior nijjples are found only 

 with the greatest difficulty, being quite minute and function- 

 less. Here, no doubt, Pseudochirus shows the actual regres- 

 sion of pouch-structures to which Hill and O'Donoghue have 

 drawn attention in their work on the reproductive cycle of 

 Dasyurus viverrinus *. 



Pseudochirus exhibits, also, primitive features in respect of 

 the number of young born. As already indicated, owing to 

 the degeneration of the anterior pair of glands and teats tho 

 maximum pouch-accommodation can be no more than two. 

 It is, however, very uncommon to find but two produced at 



* nill and O'Donoghue, loc. cit. (1900). 



