BY JAS. P. HILL. 529 



analogy with Perameles where T have shown that the common 

 median vagina is actually formed as the result of parturition, we 

 may reasonably conclude that in Trichostirus the same also holds 

 good. 



Pseudo-vaginal passage. — The genital organs (a, b, and c) of 

 three females have been examined in serial sections, commencing 

 at the level of the hinder portion of the median vagina and 

 extending backwards. , The first two sets of organs (a and b) 

 were unaccompanied by young, but, as will be pointed out, had 

 obviously been taken from females in which the young had 

 recently been born. In the third set a young one was sent by 

 my collector along with the organs. 



In (a) both uteri were enlarged, the left having been the 

 pregnant one. Its body measured 27 mm. in length by 1G mm. 

 in breadth. In a female with a young one just ready to be born, 

 the body of the pregnant right uterus measures 26 by 18 mm. 

 As before mentioned, the vaginal septum presented the appear- 

 ance of having been recently ruptured. From these facts, and 

 from the condition of the pseudo-vaginal passage, I conclude that 

 parturition had been completed only a few hours previously. 

 In section the posterior portion of the median vagina is seen to 

 lie in the connective tissue, between the lateral vagina?, now 

 running parallel with each other and the neck of the bladder. 

 Posteriorly as the sections are traced back, the lumen of the 

 epithelially lined vagina is found to be directly continued back, 

 after the disappearance of the lining as a large quite irregular 

 cleft— the pseudo-vaginal passage — in the connective tissue 

 ventral to the lateral vaginae. As in Perameles and Basyurus, 

 the passage is bounded solely by connective tissue, in which 

 indeed it appears as a mere tear, presenting as it does every 

 appearance of having been caused by mere mechanical rupture. 

 In outline it is quite irregular owing to the presence of inward I}' 

 projecting shreds of connective tissue, while fragments of the 

 same occur free in the lumen. The formation of the passage has 

 been accompanied by a considerable extravasation of blood, large 

 and small clots occurring in the tissue both in and around the 

 34 



