208 



BRITISH BUTTERFLIES. 



segments until, on the 8th, there is practically only a median hump. 

 On the 5th to 8fch abdominal segments, there is a tendency to a 

 transverse (subsegmental) division across dorsum, so that that on the 

 7th abdominal, that looks very like the trace of the glandular opening, is 

 probably not so ; there is no indication of glands on the 8th abdominal. 

 The spiracles are very large, with radiating grating (?) closing them to 

 the centres, the margins have rounded lappets all round reminding 

 one of the petaloid hair-bases, or, perhaps, of the lenticled spiracles in 

 B. guercus ; above each is a group of twelve to twenty lenticles, which 

 are continued less plentifully up the whole " slope " to base of dorsal 

 hump. On the hump itself they are wanting, probably completely, as 

 none are detected, and elsewhere they are fairly conspicuous. The 

 prolegs each carry two curves, just joined (the two pads), of hooks, in 

 two sizes alternating, about 16 in the forward sweep, and 24 in the 

 hinder, but varying in different feet. Their bases are clothed with 

 abundant, fine, colourless hairs. The skin-surface has a fine network 

 of colourless, pavement-epithelial pattern. The hair-bases have the 

 usual petaloid arrangement, but are comparatively (with those of 

 Bithys quercus, etc.) narrow and small, and are not so conspicuously 

 floral. The spiracles and lenticles have quite a smooth marginal out- 

 line. The hairs are rather short and thick, and the spiculation is so 

 short that, without some magnification and some close observation, 

 they might pass as smooth (Chapman). 



Variation of larva. — Kussell notes (Ent. Rec, viii., p. 104) that, 

 amongst the larvae he found in May, 1896, one was younger than any 

 of the others, and was much more deeply tinged and marked with red. 

 As they get nearer to being fullfed, he says, this marking seems to 

 become more of a yellow colour, and then the larvae are not unlike 

 those of Callophrys rubi. 



Quiescent stage of larva preceding pupation. — On May 26th, 

 1896, a larva of Strymon pruni had already attached itself to a leaf of 

 blackthorn by a white silken anal pad and slender white girth, that 

 passed round the centre of the metathoracic segment. The head was 

 quite retracted, and the dorsum had assumed an arched appearance, 

 although the venter was closely appressed to the leaf to which it was 

 fastened. The larva, in this position, gradually increases in height 

 and width from the prothora.cic to the 3rd abdominal segment, and 

 then narrows again to the anal segment. The 2nd, 3rd, 4th, 5th, and 

 6th abdominal segments bear a double longitudinal serrated ridge, in 

 the form of a series of raised points on either side of the mediodorsal 

 area, which forms a furrow between the two ridges. This furrow 

 narrows posteriorly, and ends in a point on the anal segment. The 

 absence of jhe ridge on the thoracic and 1st abdominal segment, 

 makes the dorsum slope rapidly from the 1st abdominal to the head. 

 The colour of the larva at this stage is yellowish-green, the apices of 

 the ridge-points purplish- red, externally edged with yellowish, the 

 central furrow rather darker green than the ground colour. The skin 

 is thickly sprinkled with short black bristles ; these are mixed with 

 longer brownish hairs on the thoracic segments, with longer white 

 hairs along the sides, and purplish hairs on the dorsal ridges. The 

 segmental incisions are deeply cut, causing the segmental sections 

 of the ridges to appear to be pointed backwards. Thorax: The 

 prothorax is narrow, but protuberant, and covers the retracted 



