I] STRUCTURAL AND SYSTEMATIC 13 



with a muscular sac containing the long and orna- 

 mented seta referred to in describing the various 

 external orifices. It will be noticed that the sperm 

 duct has no direct connection with these glands but 

 only indirectly through the external gutter which 

 connects the three male orifices of each side of the 

 body. Segments ix-xii inclusive contain certain 

 sacs which depend from, and are formed as out- 

 growths of, the septa of those segments. These are 

 the sperm sacs in which the male germ cells undergo 

 their development. A corresponding body (but very 

 much smaller) is sometimes found in relation to the 

 ovary but has not been actually described in the 

 particular species dealt with here. Finally, in segments 

 VIII and IX are a pair (that is four altogether) of 

 roundish sacs, with two or three minute diverticula, 

 known as the spermathecae. In the diverticula of 

 these sacs are stored the sperm derived from another 

 individual. 



This completes the general sketch of the structure 

 of JSfotioclrilus tamajusi which we have selected as a 

 type. In this same genus are a large number of species 

 which differ from that selected in various small 

 structural points. Thus inA^. annectens (Beddard), a 

 species from New Zealand, the spermaries and ovaries 

 are attached to the posterior, instead of to the anterior, 

 wall of their segments, and there are neither calciferous 

 glands nor modified setae upon segments xvii and xix. 



