POLYOMMATUS ICAKUS. 199 



between them, occupying much of the space between the dorsal ridge 

 and spiracles ; still the general effect is of a very unicolorous larva ; 

 the dorsal ridges have a shallow dorsal groove, which presents a small 

 pit at front of each segment. The larva is of very uniform width up 

 to close to each end ; seen from above, the segments are well separated 

 by a deep incision, and each segment is slightly convex, and three 

 hairs on the flange still show themselves, as more pronounced than 

 the others ; seen laterally, the mesothorax forms a hood high over 

 prothorax, the segments behind are not far from a general level, the 

 humping being slight ; each dorsal ridge has two very long hairs rather 

 upright, and tw T o shorter deflexed, with many others. The larva is dis- 

 tinctly a hairy one (white spiculate hairs with black bases), laterally, the 

 longest are about 05mm., and the longest dorsal about - 6mm. ; they 

 are much shorter on the 7th, 8th, 9th, and 10th abdominal segments 

 dorsally, but, even here, are fairly developed hairs, not short clubs. The 

 slopes have a considerable number of longish hairs (O06mm. to 0*2mm. 

 long). All the dark hair-bases have a circle of spicules, much the smallest 

 on the longest hairs ; round the dark raised spiracles are a good many 

 spiculate lentieles, which are also scattered elsewhere, especially abun- 

 dant on the dorsum of the 7th abdominal segment behind the honey- 

 gland ; on the 7th abdominal segment is the transverse glandular slit, 

 and on the 8th abdominal segment are the post-spiracular eversible 

 glands, with some membrane everted. The pale prothoracic plate is 

 ill-defined, if at all ; it carries ordinary hairs, two specially long ones, 

 and some lentieles. Each pad of the prolegs has eight or nine hooks, 

 rather in a group than in lines; central white pad large, each group has 

 especially one very large hook. Head black, smooth. The legs faintly 

 tinted ; the general surface has a reticulate or pavement pattern, 

 but, along the front edge of prothorax is a band of recurved spicules ; 

 these may have the effect of preventing anything insinuating itself 

 between the head and this invaginated membrane when the head is 

 retracted ; there is a tube of membrane connecting head to prothorax 

 about twice the length of the head. Some of the lentieles are spiculated. 

 Same instar (fullgrown) : Very fat little larva about 6mm. long ; colour 

 dark green with paler lines (or lighter green with dark lines, but as 

 the light green represents yellow markings, the former is best). One 

 ^specimen has the lateral lines distinctly yellow ; on the slope are three 

 oblique pale lines, the lowest, a wider cloud about spiracles ; they are 

 but little oblique, and might be called three longitudinal pale lines, 

 but that they are lower at posterior border of segment, and range 

 better with the one below in following segment than with their own ; 

 hairs longish. The dorsal ridges are pale, dark between, ridge about i 

 of slope, nearly level as seen from front ; crest of brow T n hairs on ridges ; 

 as seen laterally the ridges are rounded, and but slightly acuminate. 

 Fourth (and final) instar : When somewhat grown in this instar, 

 9mm. long, 3*6nim. broad ; colour green with darker dorsal lines, and 

 pale bristles along the dorsum and lateral flange, with fewer on slopes, 

 but a good many very much smaller hairs ; spiracles pale, and eversible 

 glands on the 8th abdominal segment conspicuously pale ; the dorsal 

 flange with faintest suspicion of yellow ; the head black, polished. 

 Another larva is 11mm., both rather thick; both have a yellow lateral 

 line along flange. Between the dorsal ridges is a distinct groove, flange 

 to flange about 08mm., length of slope 2mm. ; there are, as slightly 



