240 FRANK E. BEDDAED. 



in question. They are unusually abundant in both Hyperio- 

 drilus and Heliodrilus — more so than I have observed in 

 any other earthworm. In places each individual fibre was 

 separated from its neighbours by quite large spaces filled with 

 corpuscles. 



§ Setse. 



The arrangement of the setse is somewhat peculiar ; the more 

 dorsally situated pair, which are in reality lateral, and not 

 dorsal, are closely approximated ; the ventral couple (fig. 12) 

 are at some distance apart ; the distance separating the 2nd 

 from the 3rd seta^ is twice that which separates the 1st from 

 the 2nd. The arrangement of the setse is such as to produce the 

 impression that there are only three on each side of the body. 

 It appears to me possible that Kinberg^s genus Tritogenia 

 has the setse arranged in this way, having thus led Kinberg to 

 make the statement that it possessed only six setae per somite. 

 Perrier, who has (9) re-examined this genus, has discovered 

 that there are eight setae in each segment ; the position of the 

 male generative pores of Tritogenia between the 16th and 

 I7th segments (according to Kinberg) is another point of 

 similarity between the two genera, which are very likely 

 identical. 



No other known genus of Eudrilidse has the setae arranged 

 in this way ; there appears, however, to be a slight difference 

 in Nemertodrilus griseus in the distance which separates 

 the individual seta of each couple ; this is a step in the 

 direction of Hy periodrilus. 



§ Epidermal Sensory (?) Organs. 

 The epidermis of this worm is furnished with certain curious 

 structures of doubtful nature, identical with those which I was 

 the first to describe in Eudrilus, 



As Rosa has indicated the presence of these structures in 



Teleudrilus, and as I have found them in Heliodrilus, 



they may be regarded as characteristic of the Eudrilidae, 



and, as far as our present knowledge goes, confined to that 



' The first seta is that nearest to the nerve-cord. 



