PLEBEIUS ARGUS. 215 



with very fine, but rather long, spicules ; the other hairs on this segment 

 are three along the front margin of plate, one near its outer angle, two 

 well in front of spiracle, and the two smaller marginal ones 4 ; a large 

 lenticle in front of spiracle. On the mesothorax there are the usual hairs 

 of tubercles i and ii in a posterior position, with another i and ii (?) with 

 a large lenticle between them in front ; there is a very short clubbed 

 hair in position of iii, with four flange-hairs below, and two smaller 

 marginal. The metathorax is just like the abdominal segments except 

 in having only one lenticle, and, of course, no spiracle. The 1st 

 abdominal segment differs from the others in having a large lenticle in 

 front of spiracle. The 2nd abdominal segment has a lenticle in place 

 of the posterior of the two marginal hairs. The 3rd to 6th abdominal 

 segments have a lenticle between these two marginal hairs, and, in 

 addition to them, the 7th and 8th abdominals want one of the hairs, 

 that is, have a lenticle and one hair only. The 7th abdominal has 

 no hairs on ii, and none on iii (but there are two hairs above spiracle). 

 The 8th abdominal wants the small hair in front of i, present from 

 the 3rd thoracic to the 7th abdominal segment, and has i and the two 

 lenticles almost fused together. The flange-hairs of the 8th, 9th, and 

 10th abdominal segments cannot be definitely assigned to their 

 several segments. The two supraspiracular hairs (iii ?) deserve fuller 

 description, as being one of the items in which these species of "blues" 

 differ most from each other in the first instar. They are small, about 

 as long as the height of the base of i, much the same as those on the 

 anterior margin of the segments, viz., 0-03mm. as a maximum, some 

 rather shorter; the front one is rather longer, a little directed down- 

 wards, and with sometimes a slight curve ; both are club-shaped, i.e., 

 widening all the way to the rounded end, the posterior one a little 

 more expanded in proportion to its smaller size and directed slightly 

 forwards ; both are armed with very minute spicules. These, as well 

 as those on the other hairs, are very transparent and difficult to see ; 

 they are plainest on ii, which is slightly clubbed or thickened and 

 curved, so as to have something of the scimitar-form, with spicules 

 well-developed along the convex margin. The general surface is 

 closely crowded with rather sharp skin-points. Each (front and back) 

 pad of prolegs has a large and a small hook ; on the anal claspers the back 

 pad has only the large hook. The legs and anal plate black, as well as 

 the bases of hairs, and abundant skin-points. Second instar (March 

 18th, 1908): When about halfgrown in this instar, 2-6mm. long, about 

 0*6mm. wide, of same width from end to end, except the actually 

 rounded ends. The prothorax is low, and it slopes backwards from 

 the 6th abdominal ; otherwise, the height is pretty level, say from 

 mesothorax to the 6th abdominal ; each segment a little raised and 

 rounded, but with no definite hump. There is a dorsal line or band 

 (in the groove or plain) narrowed at the mid-segment, broadening a 

 little on the mesothorax, and on the 8th and 9th abdominal segments, 

 and represented on prothorax by the plate, of a rich, dark red-brown ; 

 there is a similar dark line just above the spiracles ; this consists, 

 however, of several separate round patches on each segment ; above it 

 is a pale narrow line, hardly expressed in some specimens, but there 

 are three other distinct whitish tracts on each side ; the first along the 

 dorsal flanges (not the one already noticed), then a spiracular one, and 

 most distinct of all, one along the lateral flange; between the spiracular 



