RUKALIS BETUL^. 295 



stretched) a full day after the moult. Looks very like previous instar 

 as to colour and marking, but the hairs are rather altered. The " slopes " 

 quite plain and flat. Front slope also. Dorsal ridges very distinctly 

 yellow, with five or six short (1mm.) brown-tinted hairs on each 

 segment. The two ridges, however, and the valley between them, are 

 only about - 35mm. or - 4mm. across. Viewed laterally, they are 

 nicely crenulated, each hair being on a rounded base, yellow, con- 

 tinuous with the yellow line of the ridge. This depends, however, on 

 the angle of view, as the hair-bases seem to be really colourless, and 

 show the yellow only from certain directions. The yellow itself seems 

 quite subcutaneous (as is common in colours of Lycaenid larvae). The 

 head seems at first to be black, but this is true only of jaws, labrum, 

 labium, and cheeks about eyes; the parts, in fact, that are much exposed, 

 but, when on the move, the basal parts of the head are seen to be 

 ochreous, fading backwards to cinereous (no trace of green as rest of 

 larva). The slopes of each of the abdominal segments are margined 

 with about ten minute white bristles, more on the larger segments, and 

 various in the completeness of the row, and more if those, not easily 

 distinguished from the flange series, are included ; the upper point 

 dorsad and the lower point ventrad. Over the rest of the slope are 

 scattered 30 or 40 hairs of the same set as these, but even smaller, and 

 various as to direction. The} 7 tend to fall into transverse rows, 

 slightly oblique; in length they are under 0-lmm. The lateral flange 

 carries ten to sixteen hairs on each segment, directed outwards, white, 

 or nearly so, and about 1mm. in length. The yellow markings are 

 almost exactly as in last instar, two oblique lines to an abdominal 

 segment, with scraps of less obvious transverse lines in the intervals. 

 The spiracles yellow or faintly brown. The front slope is studded with 

 the minute hairs like the lateral slope. April 27th: Length 15mm. 

 The "slope" is 3-5mm. on the side of the 1st abdominal segment, 

 2-2mm. on the 6th abdominal, and nothing at the side of the 

 prothorax in front. Now that it has done some feeding, the line 

 from the 1st abdominal to the tail is not straight, but descends more 

 rapidly after the 6th abdominal segment. The 7th, 8th, 9th, and 10th 

 abdominals seem to be without dividing sutures, except the 8th and 

 9th, where is a slight sinuation of the lateral flange, and.dorsally the 

 hairs and markings of the dorsal flange terminate at a transverse line. 

 In the last skin it is difficult to make out the prothoracic plate, it is 

 rather guessed as an area that does not give any puckers or wrinkles 

 (and is, of course, of symmetrical form, and probable shape of the 

 plate); it is about l*5mm. long, and l*8mm. wide, it has a large 

 number of lenticles towards the outer angles ; the central line, 

 widened posteriorly (suture ?), is free from hairs or lenticles. The 

 hairs are very various in form and size ; along its posterior edge are 

 hairs about 0-lmm. long, of oval form, at their widest nearly one-third 

 of their length ; when sufficiently magnified they are of remarkable 

 structure, oval, of Indian club form; they have spicules arranged some- 

 thing of the pattern of a fir-cone, but, though apparently ending in a point 

 hardly raised above the surface, each runs back a long way towards 

 the base, so that what first strikes the eye is a longitudinal striation, 

 almost like that of a lepidopterous wing-scale. Here and there, over the 

 plate, are similar hairs of hardly more than half the length (0-05 mm.). 

 These graduate into others a little longer and much like ordinary 



