50 PROCEEDINGS OF THE ACADEMY OF [Jan., 



the shorter of the two developed caudal setse. I have found it only 

 as he shows in fig. 2 (PL IV, fig. 2). This spine is often quite blunt 

 and always densely plumose on both sides. At the point of insertion 

 there are several long, dorsally placed serrations extending a third 

 of the distance about the base of the spine. The innermost bristle 

 is very delicate, about as long as the outer, and plumose on its outer 

 side only. Of the two well-developed median bristles, the inner is 

 from two and one-half to three times as long as the outer. Its first 

 third is bare, the middle portion fringed with small spines, and the 

 last third finely plumose. It is longer than the abdomen and un- 

 usually wide at its insertion point. The smaller of the two developed 

 caudal setae is bare for one-quarter of its length, thence to its tip it 

 is fringed with a row of small spines on the outside and delicately 

 plumose on the inner. Between the insertion point and the beginning 

 of the outside row of spines there is often a minute fringe of hairs. 

 The dorsal median seta is quite slender, a little longer than the outer 

 apical spine, and not plumose. 



The first antennae of the female (PI. IV, fig. 3) are eleven-jointed 

 in most cases, though the ten-jointed form appears occasionally. 

 Sehmeil records only the ten-jointed form from Germany, and 

 Lilljeborg the same from Sweden in his paper of 1901. Forbes 

 states that they "may be either ten- or eleven-segmented," and 

 Miss Byrnes has noted a single individual in which the left antenna 

 had eleven, the right but ten segments. I have noted a similar 

 individual in a single case. Herrick found that ''the antenna is 

 usually ten-jointed, but frequently is eleven-jointed (?), and is much 

 shorter than the first thoracic segment." The question-mark seems 

 to indicate some doubt as to the existence of the eleven-jointed form^ 

 though subsequent workers have verified his observation in the case 

 of the American representatives of this species. It is interesting to 

 note here that the eleven-jointed form has, as far as I am able to 

 ascertain, been recorded only by the American investigators. In 

 the eleven- jointed form there is borne at the distal end of the eighth 

 segment, in place of a sense-club, a minute sensory bristle. The 

 antennae taper but little in the first nine joints, the last two being 

 considerably narrower than the others. The last joint bears an 

 unusually strongly developed seta. The armature of the other 

 antennal joints is quite uniform. The length of the female first 

 antennae is a little more than half that of the first cephalothoracic 

 segment. 



Sehmeil states the first antennae of the male are normal. I have 



