DESCRIPTIONS OF GENERA AND SPECIES 341 



Genus Pbidericia, Michaelsen, 



Syn. Enchytraeus, AucT. (in part.). 



Neoenehytraeiis, Eisen (in part.). 



DEFlBriTlOBr. Setae straight, either two to a bundle or more, in which case the 

 middle setae are much smaller. Head-pore between prostomium and buccal 

 segment, dorsal pores also present. Salivary glands always present. Dorsal 

 vessel springs in nearly every ease behind the clitellum ; blood colourless. 

 Spermathecae, as a rule, with appendices. Copulatory glands sometimes present. 



K it is a little difficult to define Enchytraeus (s. s.) there can be no difficulty in 

 distinguishing the present genus. The most conspicuous character is undoubtedly 

 the presence of dorsal pores, which are not found elsewhere among the Enchytraeidae, 

 save only in the doubtful (according to Udb) instance of Enchytraeus humicultor. 

 Another matter in which the genus is peculiar concerns the setae ; these are developed 

 in each bundle two at a time ; the next youngest pair lie within the first-formed, the 

 following within these, &c. ; the result is that, in a bundle, the two outermost setae 

 are the oldest and longest, the innermost the youngest and shortest; sometimes the 

 symmetry of the arrangement is spoiled by one seta falling out; in the species 

 F. bisetosa it appears that the older pair falls out before the next is developed ; hence 

 this worm has two setae only in each bundle. This remarkable and interesting mode 

 of development of the setae in Enchytraeids was first made known by Vejdovskt in 

 his work Upon the Enchytraeidae (3). 



MiOHAELSEN allows eleven species^ of Fridericia, to which may be added my 

 species F. antarctica, which may be distinguished from each other by the following 

 table : — 



I. Spermathecae without diverticula. 



i. Salivary glands branched P. striata. 



ii. Salivary glands not branched F. bulbosa. 



' Enchytraeus vermiiybUaris of Clapae^de (3, p. 55) seems to be undoubtedly a Fridericia, since it has dorsal 

 pores (3, PI. ii. figs. 10, 11). The absence of diverticula to the spermathecae ('les receptacles de la semence 

 . . . ressemblent beaucoup a ceux du Pachyckilus semifuscus ') places the species in the neighbourhood of F. striata 

 and F. bulbosa, from both of which it differs in that the anteseptal part of the nephridium is long, but has 

 a straight duct. 



