136 OLIGOCHAETA 



no means universal in the group ; neither do they occur in every genus belonging 

 to those families in which they have been met with. At present they are known 

 to exist in the following families only :— 



Naidomorpha? Geoscolicidae (Criodrilus). 



Tubificidae. Eudrilidae (Polytoreutus). 



Lumbricidae. Eclipidrilidae. 



In the Naidomorpha Lankester (9) has described spermatophores in B'ais 

 serpentina. They are figured by him as long -coiled aggregations of spermatozoa 

 more or less similar to the immature spermatophores of the Tubificidae, but entirely 

 lacking the complicated structure which these bodies show when fully ripe. Vejdovskt 

 (24, p. 153) could not, on the other hand, find any definite spermatophores in the 

 Naidomorpha. 



Among the Tubificidae the spermatophores have been known for a long time. 

 They wore figured by Duges (1, PI. VII, figs. 2, 4) in Tubifex {' Nais filiformis'), 

 and termed in the description of the plate ' animalcule spermatique.' In the text it 

 is suggested that they are too large to be probably so designated. Budge, though 

 noticing the same structures, made no suggestion as to their nature. 



Lankestee has given a more detailed account of the spermatophore of Tubifex 

 rivulorum in a subsequent paper (2), which is copiously illustrated. The sperma- 

 tophore has a long, worm-like form, and generally a conical head with a collar just 

 below; its peculiar form is due to the fact that it is moulded in the interior of the 

 • spermatheca. The spermatophore is composed of a cementing matrix in which are 

 imbedded the spermatozoa ; when fully formed it has rather a complicated structure. 

 Centrally there is an axial band, apparently a canal, but filled with granular 

 matter and darkly stained by carmine. External to this is a narrowish, highly- 

 refringent band, and following this a broad band in which are imbedded the 

 spermatozoa ; these are imbedded parallel to each other and run obliquely ; externally 

 to this is another highly refringent layer, and beyond this project the ends of the 

 spermatozoa, which are in constant vibratile motion. When the spermatophore is 

 examined in transverse section, the spermatozoa are seen to have an imbricated 

 arrangement which suggests that they have been fitted together by a twisting 

 motion. 



Fsammorydes has a spermatophore of a rather different form. Its most marked 

 peculiarity is a series of recurved booklets at one extremity ; these are figured by 

 VE.TDOVSKY (13, Taf. viii, figs. 11, 12), but not by Lankestee (2), who has also 

 described the spermatophore of this worm. Otherwise the structure of the spermato- 



