NEW ENGLISH GENUS OF AQUATIC OLIGOCHiETA. 163 



somewhat fibrillated network. The nuclei with little chro- 

 matin are chiefly on the surface of the mass, and look as if 

 they had only recently been gathered up ; the others are pro- 

 bably dead nuclei destined to undergo degeneration previous 

 to their expulsion by the nephridia. In this mass of "debris " 

 are frequently a number of yellow granules (?/), perhaps the 

 contents of chloragogeu cells which have been collected by the 

 funnel. 



§ The Generative System (fig. 11). 



The four folded digitate testes have the usual position, the 

 first pair on the anterior septum of Somite x, and the second 

 pair in Somite xi. The four ciliated rosettes, which are less 

 folded than in Lumbricus, &c., lie in these same somites. 

 Both testes and rosettes are quite free in the coelom, there 

 being no median sperm- sac. There are two pairs of lobulated 

 sperm-sacs, occupying Somites xi and xii ; those in the 

 latter somite being slightly the larger. They are attached to 

 the anterior septum of each of these somites, so that they 

 are entirely post- septal; there are no median sacs. 



The arrangement of these sperm-sacs is thus very different 

 from what obtains in Criodrilus, in which these organs are 

 situated as in Allolobophora, there being two pairs of pre- 

 septal in addition to the two pairs of post- septal sacs. 



Still greater difference is exhibited by the relations of the 

 sperm-duct. Passing from the ciliated rosette, in each case, 

 the duct is as usual slightly coiled behind the septum, forming 

 the epididymis; the sperm-duct then dips into the 

 body-wall, penetrates the muscular coats, and attains 

 a sub-epidermic position, which it retains throughout its 

 extent (figs. 19, 20, 22). This superficial position is unknown in 

 any other earthworm, nor does it occur in any Oligochsete ; and 

 if we wish to press the homology between sperm-duct and ne- 

 phridium we may refer to Libyodrilus^ for a corresponding 

 position of part of the nephridial system, which, however, as Mr. 



^ f . E. Beddard, ' Quart. Journ. Micr. Sci.,' vol. xxxii, PI. XXXIX, figs. 

 14 and 16. 



