64 FEMALE UROGENITAL ORGANS OF PERAMELES, 



degenerate and irregular remains of allantoic stalks which appear 

 in the connective tissue forming its direct continuation can only 

 be described as forming an integral part of the same, so closely 

 are they interpenetrated and surrounded by it. (Plate xii., fig. 16, 

 all.s.) As sections are traced posteriorly, the stalks become more 

 distinct and easily recognisable, but vary greatly in size, in shape 

 and in character. Surrounded and invested as they are by con- 

 nective tissue, which is now definitely intergrown with the 

 degenerate tissue of the stalks, they completely block the lumen 

 of the pseudo-vaginal passage. The tissue of the stalks is now 

 quite fibrosed and is invaded by large numbers of connective 

 tissue corpuscles. These are often found aggregated into groups 

 occupying what were originally the cavities of the allantoic 

 vessels, and, with or without such groups as a centre, other 

 corpuscles are found to have taken on a definite concentric 

 arrangement. 



Behind the terminations of the stalks, the pseudo-vaginal 

 passage can be traced back into the terminal part of the uro- 

 genital strand, situated in the rounded mass enclosing the uro- 

 genital sinus and cloaca, but here it narrows and finally disappears 

 some two hundred and fifty sections in front of the anterior end 

 of the sinus. In these sections the connective tissue in the 

 direct line of continuation of the passage is perfectly uniform in 

 character, and exhibits not the faintest indication of the previous 

 existence in it of the cleft by way of which the young reached 

 the exterior. 



V. /'. obesula, with several 4 cm. young. 



Only portions of the urogenital strand and the urogenital sinus 

 were examined in this specimen. 



Sections through the anterior portion of the urogenital strand 

 reveal features very similar to those described for the preceding 

 specimen. In fig. 17 the greatly degenerate remnants of the 

 allantoic stalks {all.s.) are seen to almost completely block up the 

 pseudo-vaginal passage. They are closely surrounded and inter- 

 penetrated by connective tissue and in places appear to be directly 



