25 



segments (Plate V, Fig. 24.) ; the first sub-rotund ; the second club 

 shaped ; the remainder slender. The following is the usual formula 

 of the comparative length of the segments :* 

 2 — 5 — 10 1-2 — 4 — 6 — 4 — 4. 



The following formula shows the range of variation observed, 

 omitting the two basal segments, which are fairly constant and which 

 can seldom be measured accurately in mounted specimens : 



(9-1 1)— 4— (5-6)— (4-5)— (4-5). 



The entire length of the antenna is about one-third the length 

 of the body. The second segment bears a few short spines, and the 

 apical segment bears a short spine at its tip. The third, fourth, 

 fifth and seventh segments have one or more sense organs near their 

 outer ends. These seem to be always absent on the sixth segment. 

 The third to seventh segments, inclusive, are annulated. 



Immediately below the eyes is a short sub-conical structure 

 (rostrum of Maskell), from the apex of which the mouth setae appear 

 to arise. The rostrum (mentum of Maskell) consists of four free 

 segments and a basal apparently immovable portion, which is at- 

 tached to the body seemingly to the prothorax between the bases of 

 the fore legs. The basal portion reaches about to the tip of the coni- 

 cal structure (rostrum of Maskell), and the four following segments 

 show the following proportionate lengths : 4 — 7 — 5 — 12. The ros- 

 trum bears a few scattering hairs, which are more numerous on the 

 terminal segment. The labrum, which is very slender at the tip, 

 reaches to the outer end of the first movable segment of the ros- 

 trum. 



The thorax is rather short, compact and well rounded above. 

 The prothorax is slightly smaller than the metathorax, which in turn 

 is smaller than the mesothorax. The sclerites which compose these 

 divisions of the thorax are well fused. The two anterior pairs of 

 legs are of about equal length. The fore coxae are slightly longer 

 than the middle coxae ; the trochanters are short ; the femora about 

 two-thirds as long as the tibiae and about equal to the two tarsal seg- 

 ments together ; the first tarsal segment is about one-fourth longer 

 than the second. The hind coxae are very stout, with a prominent 

 infolding anteriorly. The hind trochanters are short, each bearing 

 a single spine at the bottom of a groove-like cavity on the caudal 



* Measurements made with i in. eyepiece and 1-2 in. objective; tube length 145 mm. 



