360 



ON AaUATIC OLIGOCH^TOUS WORMS. 



[May 3, 



present species with some allied forms. The table (p. 359) gives 

 some additional facts not referred to in the above description. Also, 

 I introduce a few worms not yet fully described, which I have 

 recently been studying. 



Tlie position of the external apertures of the male reproductive 

 apparatus is, however, rather diflferent from what is found in the 

 genus Acanthodrilus. The accompanying figure (fig. 2) illustrates 



Fis. 2. 



Ventral surface oi Kerria halophUa, to show generative apertures. 

 8p, Sperm atothecal jjores ; od, oviducal pores ; At, atrial pores ; Sp.d. spermi- 



ducal pores. 

 The segments of clitellum are indicated by Eoman numerals. 



the arrangement in an individual which was studied by means of 

 longitudinal sections ; I found it impracticable to examine the ven- 

 tral surface of the entire worm mounted in glycerine, for the reason 

 that in the course of preservation a good deal of the corrosive sub- 

 limate used as a fixing reagent had crystallized upon the integument, 

 rendering it therefore very opaque, "in the sections the setae were 

 seen to be quite unaltered upon the genital segments, they were not 

 even larger than those upon the neighbouring segments. The atrial 

 pores, as well as those of the vas deferens, are in close relation to 



