ON TWO NEW GENEKA OF AQUATIC OLIGOCH^TA. 289 



§ Spermathecce. 



There is only a single pair of spermathecse in this genus, which are situated in the 

 Xlllth segment (fig. 5, sp.) ; at least, their external orifice is placed in this segment, in 

 front of the dorsal setae. The pouches themselves are extraordinarily elongated, and 

 extend into the XVth segment. 



Each spermatheca is coiled upon itself once or twice ; the lumen is at first tolerably 

 wide and the external pore is large. At this point the epidermis can be seen to be con- 

 tinuous with the cellular lining of the spermatheca. One spermatheca had the form 

 illustrated in figs. 5, 10. The former figure represents the genitalia of Phreodrilus 

 as they would be seen on a dissection of the worm ; it is, however, compiled from a 

 single continuous series of longitudinal sections, of which not a single one was missing. 

 Fig. 10 represents the spermatheca in longitudinal section. The wider portion of the 

 spermatheca referred to passes back towards the posterior end of segment XIII ; it is 

 then bent upon itself, and runs back to a point about opposite to the external orifice. 

 The spermatheca then passes down to the ventral side of the body with a gradually 

 decreasing lumen ; arrived at this point it comes to lie between the ventral blood- 

 vessel and the nerve cord ; the tube is then directed backwards, running still between 

 the blood-vessel and the nerve, and perforates septum XIII/XIV ; in the XlVth 

 segment the spermatheca again becomes wider, and lies no longer beneath the ven- 

 tral blood-vessel ; its course is nearly perfectly straight, and after perforating inter- 

 segmental septum XIV/XV without any decrease of its width, it terminates 

 blindly in the interior of the XVth segment at a little distance from the septum last 

 traversed. The constriction of the spermatheca in the middle, which amounts to an 

 actual occlusion of the lumen in the individual studied by me, recalls the spermatheca of 

 Anachceta Eiseni figured by Vejdovsky [8, pi. vii. fig. 22]. 



I could not discover any spermatozoa in either of the two spermathecse, and they pre- 

 sent an appearance of immaturity, owing to the non-glandular character of the lining- 

 epithelium. The immaturity of the spermathecse, therefore, corresponds to the immature 

 condition of the ova and oviducts. 



The minute structure of the spermatheca presents no character of any particular 

 importance. It is covered externally by a circular layer of muscles, and has a lining of a 

 single layer of cells. Its structure corresponds exactly to that of the diverticulum of the 

 vas deferens. 



The position of the spermathecse is that of certain of the Lumbriculidse. In all the lower 

 groups of Oligochseta, as well as in all Earthworms excepting only Microchcela, Brachy- 

 drilus, and some of the Eudrilidse, the spermathecse lie in front of the ovarian segment. 



Furthermore, the great length of the spermathecse, and the fact that they extend 

 through more than one segment, is a peculiarity almost confined to the genus Phreodrilus. 

 The only other example that I can recall is the Eudrilid Heliodrilus [see Beddard, 11], 

 where the spermatheca extends through three or four segments. 



VOL. XXXVI. PART II. (NO. 11). 2 X 



