PLEBEIUS ARGUS. 219 



lines just below it. The change from a russet (olive and brown) to a 

 green coloration is rather striking, occurring just as the larva becomes 

 full-fed in this instar (not preparing to moult). In the third instar 

 there are still, especially on the abdominal segments, longer hairs, that 

 may be regarded as i and ii ; lor instance, on the 3rd abdominal there 

 are, on each side, two long dorsal hairs, that are probably i and ii, the 

 posterior, however, rather the longer (04mm.). From the dorsum 

 down to the spiracle, each side has about 30 hairs, only one or two as 

 long asOOomm., with one dorsal, and three or four spiracularlenticles; 

 these short hairs are mostly somewhat scimitar-shaped. The head is 

 about 0'7mm. across, the prothoracic plate about Oomm. ; the latter 

 carries eleven or twelve hairs on each side ; the flange and marginal 

 groups each have about ten hairs, with a lenticle or two ; one of the 

 hairs rather larger than the other (0-2mm.). The hair-basps all have 

 stellate processes ; these are generally somewhat sharply-pointed, 

 rather below the middle of the conical base, point upwards, and have 

 ridges running down from them to the skin-margin of the cone. 

 Lenticles have similar processes, but they are smaller, more rounded, 

 and close to their upper margins. There are comparatively few 

 lenticles; there is a large flight round the honey-gland, especially 

 along its posterior border, and at each end there are two or three 

 special hairs about O'Oomm. long, gradually expanding, and more 

 suddenly at the tip (like a flower of Datura or tobacco), where the 

 spicules form a margin, but these hairs vary a good deal from specimen 

 to specimen. The gland is a slit 0*4mm. across. The eversible fans 

 are well-developed, and each has some 24 or so rays or hairs. The 

 pads of the prolegs have each four to five, or even three to six, hooks 

 of varying sizes, so that only one might be called long, or only one 

 short. The anal claspers have five or six hooks on each pad, three 

 long and three short, or often on posterior pad one very long one. In 

 this skin the variation from specimen to specimen, in the size, form, 

 and distribution of the hairs, is greater than in the second instar. 

 The skin-points are closely set everywhere, their chitinous tops show 

 four or five lines radiating down from the apex. Fourth (final) instar 

 (newly-moulted, April 15th, 1908): The head about 0*9mm. across, 

 the prothoracic plate about 0'8mm. The larva, 8 # 5mm. long, much 

 resembles Buckler's figure. The green slopes (with pale lateral line) 

 are modified in tone by the abundant, almost yellow, hair-bases, at 

 present (the larvse not having yet grown) very crowded together. The 

 broad, deep red-brown (almost black) dorsal band, is bordered on each 

 side by yellow ; it narrows backwards, but, on the 7th and 8th 

 abdominal segments, has a wide extension into, or, one might say, is 

 interrupted by, a paler shield-shaped mark, reaching out to the lateral 

 dark oblique line on the 7th abdominal, and narrowing again to a 

 point on the 8th abdominal. Broader on the mesothorax, it similarly 

 broadens out into a scutcheon on prothorax, which appears to be the 

 prothoracic plate. The slope (above the pale lateral flange-line) has 

 six lines, the first above the flange-line, a narrow darker green, then a 

 rather yellower one, then two oblique darker lines, separated by a 

 paler (yellowish) one, then an upper area, only a little less than the 

 whole breadth below it. The oblique lines (downwards and backwards) 

 do not slope much, but are by no means evenly longitudinal. There 

 are longer, brownish, dorsal and lateral flange-hairs, and some between, 



