252 SEMINAL BLADDERS. 



be determined), by four apertures on each side. In a section 

 made through the part of the wall of the cloaca containing the 

 openings of the ureters of both sides, there were present on the 

 left side (where the section passed nearer to the surface than 

 on the right) four small openings posteriorly, viz, the openings 

 of the ureters and one larger one anteriorly, viz. the opening of 

 the Wolffian duct. On the other side of the section where the 

 level was rather deeper, there were five distinct ducts cut 

 through, one of which was almost on the point of dividing 

 into two. This second section proves that, in this instance at 

 least, the two ureters did not unite till just before opening into 

 tlie urinogenital cloaca. The same section also appeared to 

 shew that one of the ureters fell not into the cloaca but into 

 the Wolffian duct. 



As stated above both the Wolffian duct and the ureters fall 

 into an unpaired urinogenital cloaca. This cloaca communicates 

 at one end with the general cloaca by a single aperture situated 

 at the point of a somewhat .conspicuous papilla, just behind the 

 anus (PI. XIX. fig. 1, o), and on the other it opens freely into 

 a pair of bladders, situated in close contact with each other, 

 on the ventral side of the kidney (PI. xix. fig. l,sh). To these 

 bladders Professor Semper has given the name uterus mascii- 

 linus, from having supposed them to correspond with the lower 

 part of the oviducts of the female. This homology he 

 now admits to be erroneous, and it will accordingly be better 

 to drop the name uterus masculinus, for w^hich may be substi- 

 tuted seminal bladder — a name which suits their function, since 

 they are usually filled with semen at the generation season. 

 The seminal bladders communicate with the urinogenital cloaca 

 by wide openings, and it is on the borders of these openings that 

 the mouths of the Wolffian duct and ureters must be looked 

 for. My embryological investigations, though they have not 

 been specially directed to this point, seem to shew that the 

 seminal bladders do not arise during embryonic life, and are still 

 absent in very young individuals. It seems probable that both 

 the bladders and the urinogenital cloaca are products of the 

 lower extremities of the Wolffian duct. The only other duct 

 requiring any notice in the male is the rudimentary oviduct. 

 As was first shown by Semper, rudiments of the upper ex- 



