NO. 6.] ACCOUNT OF THE SPECIES. 109 



a ledge of the outer edge, rather in front of the middle. The latter seta is 

 very small, and this is also the case with the outermost of the apical setae. 

 The innermost seta is about twice as long, and distinctly ciliated, like the 2 

 middle ones. The latter are much longer than the others, though somewhat 

 unequal, the inner one being considerably longer than the outer, and some- 

 what exceeding half the length of the tail. Moreover, from the dorsal face 

 of each ramus an extremely delicate bristle arises, not indicated in 

 the figure. 



No trace of eyes is to be detected, and, indeed, the total absence of 

 these organs is a character common to all the species of this genus. 



The anterior antennae (fig. 3) are shorter than the cephalic segment, and 

 are angularly bent at the base. They are composed of only 6 articulations, 

 the 3 proximal ones constituting a basal division, the 3 distal ones a well- 

 defined terminal part. The 3 joints of the basal division are somewhat dilated 

 and compressed, but rather unequal in size. The 1st joint is constricted at 

 the base, gradually widening distally, and carries at the end anteriorly 2 

 slender bristles. The 2nd joint is larger than the 1st, with which it forms a 

 geniculate bend. It carries 4 slender bristles, one of which issues near the 

 base from a distinct ledge of the anterior edge, the other 3 from the end. 

 The 3rd joint is about the length of the 2 preceding ones combined, and 

 gradually tapers somewhat distally. It carries 2 successive bristles at about 

 the middle of the anterior edge, and another bristle at the end. The terminal 

 part is very sharply marked off from the basal part, being greatly constricted 

 at the base, and connected with the basal part by a veiy mobile articulation. 

 It is somewhat shorter than the 3rd basal joint, and of the 3 joints composing 

 it, the 1st is much the largest, about equalling in length the other 2 com- 

 bined. This part carries several very long and slender bristles, 5 of which 

 issue from the tip. 



The posterior antennae (fig. 4) form each a simple curved stem, consisting 

 of 3 joints, the 1st of which constitutes the basal part, the other 2 the inner 

 ramus, no trace of an outer ramus being present. The basal joint is oblong 

 and gently curved, with the anterior edge bulging considerably in the middle, 

 and carrying at the end a slender bristle. The 2nd joint is shorter than the 

 1st, but rather broad, fusiformly dilated, and quite naked. The terminal joint 

 is scarcely more than half as long as the 2nd, and carries 10 spiniform, 



