DESCRIPTIONS OF GENERA AND SPECIES 



527 



drilus as they are here defined; the chief resemblances to Benhamia lie in the 

 absence of setae ventrally on the segment which bears the pores of the sperm-ducfc- 

 pores, in the presence of two gizzards; in other respects the worm is like an 

 Acanthodrilus. 



There remain then those species which have paired nephridia, thirty-six in all ; it 

 is not, however, in my opinion possible to sort these into generic or subgeneric 

 groups. Even the genus itself, to which, of course, the name Acanthodrilus must 

 be applied, has, as its only positive character, the presence of paired nephridia, and 

 of a single gizzard. The following table shows the principal structural features of 

 the several genera: — 



Genus Acanthodrilus, Peeeiee. 



Syn. Mandane, Kinbeeg. 



Lumbricus, Geube (in part.). 



Hegesipyle^, Kinbeeg. 



DEFiNiTioir. Acanthodrilidae, with paired nephridia, the external pores of which 



either alternate in position from segment to segment, or, if fixed, are in front 



of one of the lateral couples of setae. Gizzard single. Calciferous glands present 



or absent. CUtellum, XII (XIII)-XVI (XIX); no genital fossa. Penial setae 



rarely absent. 



' Fide Pekkiee. 



