THE ANATOMY. SPERMIDUCAL GLANDS 113 



I select Kynotus michaelsenii as the type of the Geoscolicidae, as it has been 

 very carefully described by ROSA, though unfortunately his description is unaccom- 

 panied by. any illustrations. 



The terminal apparatus of the male efferent ducts in this Annelid consist on 

 each side of the body of a long oval muscular sac extending through four segments ; 

 posteriorly and externally a long tube arises from this which reaches back through 

 another seven segments ; the terminal sac is attached to the parietes not only by its 

 own walls, but by a moderately long muscular slip. The terminal sac has very 

 thick walls, which as a consequence reduce the extent of the lumen ; its interior is 

 divided by an incomplete septum into two chambers ; the upper of the two chambers 

 is furnished with a shield- shaped thickening of the internal wall, on to which opens the 

 glandular appendix to be presently described. The epithelium lining the ventral surface 

 of the two chambers is like the external epidermis, but has rather more numerous 

 glandular cells ; the dorsal chamber, on the other hand, is lined by a tall columnar 

 epithelium without glandular cells like those of the lower chamber, but with 

 glandular cells staining deeply with carmine ; the entire sac has a chitinous 

 lining. The glandular appendix already spoken of opens on to the shield-shaped 

 projection of the upper chamber ; the canal which there opens has the same minute 

 structure as that of the sac into which it opens ; this becomes further back a tube 

 lined with two layers of epithelium as in Acanthodrilus, &c., ensheathed in a 

 common peritoneal coat which does not follow the windings of the contained tube. 

 The sperm-ducts penetrate the terminal sac near to its external orifice and pass 

 along the thickness of its wall, finally opening into the lumen of the glandular 

 appendix where it retains the non-glandular character of the terminal sac. ROSA 

 considers that the organ in the Geoscolicidae is not the homologue of that of other 

 Oligochaeta and terms it ' Pseudo-prostate.' 



It does not, however, appear to me to be possible to draw this hard and fast 

 line between the Geoscolicidae and the Megascolicidae that ROSA wishes to draw ; 

 in the first place, as I have attempted to show, the Eudrilidae seem to agree more 

 nearly with the Geoscolicidae than with the Megascolicidae ; in both of them the 

 essential difference is in the presence of a muscular terminal sac into which the 

 spermiducal gland proper or the glands in the case of most Eudrilidae open. ROSA 

 has, I think, overlooked the fact that in the genus Perickaeta something of the same 

 kind also exists. In the systematic part of the present work I have laid some little 

 stress as a specific character upon the fact that in some species the narrow muscular 

 duct of the gland does not communicate directly with the exterior, but opens 

 into the interior of a variously-sized sac ; this latter may be of large size, as in 



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