the Life History of Agriades ther sites. 291 



hairs as a liiic down each side of dorsum, and a lateral series are 

 very evident and nearly as long as the thickness of larva. As the 

 larva grows, reaching a length of 1'5 mm., or when stretched nearly 

 2 mm., it develoj^s some very distinct colouring. The ground- 

 colour is a very pale olive-green with a nearly white band along the 

 prominence of the lateral flange. Along the dorsal tubercles (with 

 black bases), and again just above the spiracles, the ground-colour 

 remains as pale bands, medio-dorsally is a broad pale brownish 

 band hardly interrupted at the incisions; between the two pale 

 bands each segment has a pale brownish patch of same colour as 

 the dorsum, as are all the dark portions, or rather four small patches, 

 one at each corner of the area, the two dorsal ones touching each 

 other, the other two separate and having the lenticles medially on 

 a pale area, the spiracles are each on a pale area, but surrounded 

 by a dark nearly square j)atch, which is, however, sometimes actually, 

 at others nearly, obsolete just over the spiracle, connecting the pale 

 spiracular patch with the pale band above it, the prothoracic plate 

 is pale and the skin pomts are everywhere obvious as minute black 

 points, the hairs are colourless, glistening and spiculate, their bases 

 and the lenticles are black and conspicuous on the paler skin. 



When we compare the armament of hairs, lenticles, etc., 

 of the 1st stage larvae of icarus and thersites, it seems at 

 first impossible to detect any difference ; there is, however, 

 a trifling difference, in that the hairs on A. thersites are 

 about an eighth longer than on P. icarus. So small a 

 difierence is rather astonishing after the very marked 

 difference in the eggs, but is not really so when one observes 

 that these larvae cannot be distinguished from those of 

 bellargus and coridon and even semiargus, by any greater 

 differences 



PI. XXXVII and XXXVIII show the skins of the two 

 larvae of the two species at this stage. 



Sept. 5. In the 2nd instar the larva is about 1 "5 mm. long approach- 

 ing 2*00 according to attitude and age in the instar. In form the 

 dorsal flanges stand out more prominently, with a flat dorsal plane 

 between them and very definite side slopes, each rather fiat, from the 

 dorsal to the lateral flange and at an angle of about 90° to its fellow. 

 The dorsal plane has just a trace of a central depression or valley 

 emphasised by the large hair bases on the flange, the plane is nearly 

 twice as wide in front (on mesothorax) as behind (on 7th abdominal), 

 narrowing from before backwards. The hairs are more numerous, 

 with large black bases and nearly colourless, much spiculated shafts, 

 the colour is dark olive green, compounded of faint ochreous (pale) 



