SKIN AND KEPRODUCTIVE ORGANS OF NOTORYCTES. 339 



and the whole length of the urethra. Indeed, so closely 

 bound together are these parts that a true conception of their 

 relations cannot be obtained by dissection. Notoryctes then^ 

 in this respect, also may be compared with such forms as 

 Perameles, Tarsipes. and Acrobates, and contrasted with the 

 free coiled lateral vaginae of Myrmecobius. 



Posteriorly to the median vaginal s, and occupying the 

 short space between it and the anterior extremity of the long, 

 narrow, urogenital sinus, there lies a mass of dense deeply- 

 staining connective tissue (text-figure, and PI. 20, fig. 16, 

 s.c.t.) exactly similar in appearance and position to that in 

 Perameles [4, p. 54, 55], and other forms, through which in 

 Perameles birth takes place. Careful examination of this 

 part in Notoryctes has failed to show any indication of a split 

 such as occurs in other forms, such as Perameles, Tarsipes, 

 Macropus, Trichosurus, and Dasyurus, but it is open to ques- 

 tion whether this means that the animals examined had not 

 borne any young-, as might possibly be indicated by the 

 absence of spermatozoa and their accompanying secretion in 

 the ducts, and by the general appearance of the parts, or, that 

 parturition having taken place similarly to Perameles, the 

 epithelium has been completely renewed, as in Perameles and 

 Dasyurus, and even the split in the connective tissue has been 

 quite closed, as in Dasyurus also. 



Certainly, unless these animals were virgins, there is here 

 no permanent pseudo-vaginal passage [cf. Acrobates], and 

 even were they not so, the connection between the two median 

 vaginal canals, shows no trace of any such forced opening as 

 occurs at birth in older forms of Perameles and Acrobates, 

 so that we may infer that a median vaginal connection is 

 normally present, as in Petaurus. 



At the same time, I should judge that birth takes place, as 

 in Perameles, through a pseudo-vaginal cleft in the connective 

 tissue, and not through the lateral vaginal canals. 



We may notice particularly in concluding this part — 



(1) The sharply marked distinction between the uterine 

 and vaginal parts of the ducts. 



