306 



PARASITIC WORMS. 



twisted condition described by Eatzel. The spicules are alate, 

 and almost the whole spicule is twisted in gimlet fashion about 

 its longitudinal axis, the only part not involved being a 

 short portion near the root. Ratzel suggested that this 

 twisting of the spicules might be, at least in part, due to 

 long immersion in alcohol, and was not inclined to lay much 

 stress upon it as a specific character. There seems, however, 

 to be no reason 

 for believing 

 that it is not a 

 normal and 

 constant c h a- 

 racter of the 

 species. The 

 accessory piece 

 (figs. 2, a. p., 

 3) is, as Ratzel 

 states, 0.15 

 mm. long, and 

 is shaped much 

 as his figures 

 indicate, t h o- 

 ugh these are 

 somewhat 

 diagram - 

 matic. The or- 

 gan is largely 

 hollow, having 

 a large open- 

 ing near i t s 

 broad anterior 

 end, on the 

 dorsal side. 

 The anterior 

 edges of this 

 aperture are 

 produced later- 

 ally into blunt 



angles, and from each of these a small flange is reflected 

 dorsally and posteriorly, giving the anterior end of the 

 organ a hooked appearance in lateral view. The caudal 

 papillae were not described by Eatzel. Of these there are ten 

 pairs, fig. 2, the third pair from the tip of the tail being some- 



Fig. 2. 



Subulura perarmata. Caudal end of male; 

 lateral view, a-p, accessory piece. 



