CELASTRINA ARGIOLUS. 435 



lateral edges of the segments are much crenulated, due to the depth of the incisions, 

 and with a rather paler (yellowish) lateral line. The ventral surface is darker 

 down the middle (between legs) ; it is also very flat, smoother and freer from hairs 

 than the upper surface. The true legs are as pale as the ground-colour, as also are 

 the prolegs ; the hooks on the latter are reddish, and, though short, are fairly 

 strong, and cling firmly (Buckler). The head almost globular, but slightly produced 

 towards the mouth ; it is very small, not being more than one-third as wide as 

 prothorax, and entirely retractile within that segment at the pleasure of the larva ; 

 the body is of the shape of a Chiton ; the divisions of the segments are decidedly 

 marked ; the prothorax has the anterior margin semicircular, and projecting over 

 the head ; the posterior margin of the metathorax and each following segment 

 slightly projecting over the next following segment; there is a slight mediodorsal 

 depression on all these segments, so that the back appears to have a double series 

 of approximate humps, two on each segment, from the mesothorax to the 6th 

 abdominal inclusive ; the lateral margin of all the segments dilated ; the entire 

 dorsal surface is finely shagreened or sprinkled with approximate yellow glandular 

 dots, in this respect the skin having the appearance of the glandular surface of the 

 twigs or leaves of many plants, and being clothed with pale hairs. The head is 

 black and highly glabrous ; the body apple-green, with very oblique lines on 

 each side of a darker green ; these oblique lines are very indistinct ; on the 6th 

 abdominal segment is a diffused red spot, also indistinct ; the ventral surface and 

 claspers are apple-green ; the legs are almost colourless and semitransparent 

 (Newman). The fullgrown larva is also described by Prideaux (Ent. Mo. Mag., 

 xxxvii., p. 78), and ourselves (Brit. Butterflies, p. 190). 



. Larva. — First instdr (newly-hatched) : The newly-hatched larva is 

 a colourless scrap, faintly tinted, perhaps, of a yellowish -green, but of 

 no pronounced colour till, having eaten, it becomes slightly greenish. 

 The head is black, and the neck long and extensile, at least twice the 

 length of the head. The total length of the larva is at first about 

 l'5mm. The neck consists of colourless and structureless membrane, 

 the intersegmental membrane between the prothorax and the head, 

 structureless of course only in the sense that it presents no skin-points, 

 hairs or other appendages. How its extension is effected, is a matter 

 about which I have been unable to learn anything, a difficulty that 

 points rather strongly to its being secured by fluid contents being- 

 forced into it by pressure elsewhere. The extension is not required or 

 used until the larva has eaten something, and requires to follow up 

 the receding surface on which it is feeding, and consequently has 

 obtained some contents that may be forced by pressure in different 

 directions. For the structural details, arrangement of hairs, etc., see 

 pi. xxiii. The disposition of hairs and lenticles agrees very much with 

 that obtaining in Polyommatus (icarus, etc.), and differs very much from 

 that of Lampides (boeticus). It has the hairs of tubercles i and ii; that 

 of iii (?) is represented by the two clubbed hairs (as in Polyommatus), 

 instead of the ordinary hair (as in Lampides), and the hairs are all 

 spiculated (or perhaps rather serrated) as in the Polyommatid larva; 

 the chief distinction from the latter is in the large size of the clubbed 

 hairs of tubercle iii. In several of my specimens of mounted skin, the 

 skin-points are very notable, and deserve some study in connection 

 with the sculpture of the pupae of the Polyommatids. In most larvae 

 with which I am familiar the skin is divided into cellular areas (pave- 

 ment-epithelium actually, or in pattern), and the skin-points are 

 projections, one in the centre of each of these. This arrangement is 

 often well seen in pupae, the intersegmental membrane being a beauti- 

 fully tessellated pavement, and often each cell has a central darker 

 point, and these graduate into ordinary skin -points as the ordinary 

 segmental surface is reached. Here, in the larva of C. argiolus, in the 

 first instar, the skin-points are minute rounded elevations connected 



