STRYMON PRUNI. 217 



about 100 hairs, amongst them a good many stellate points, the ribs or 

 wrinklings attached to which are nearly evanescent. On each of these 

 segments the two hollows, referred to already, present darker surfaces, 

 with wrinkles radiating from the centre and free from any hairs, 

 points, or lenticles; they are, therefore, very definite structures. Their 

 positions are, if one divides the space from the dorsum to the spiracle 

 into four spaces, the dorsal spine in the dorsal division rather behind 

 middle of segment — the upper hollow will be half way from dorsum 

 to spiracle, and in middle or slightly to front of segment ; the lower 

 hollow will be on the line between the 3rd and 4th divisional spaces, 

 and decidedly towards posterior margin of segment. On carefully ex- 

 mining the pupa of Callopkrys rubi, the representatives of these marks 

 may be recognised, a little lower on the segment, and consisting of a 

 minute area, darker, and with more marked ribbing, and without hairs, 

 lenticles, or points. The 5th, 6th, and 7th abdominal segments are 

 very weak in the ventral line, in one specimen discontinuous, but for a 

 delicate membrane, and behind them is no very definite structure except 

 finely granulated membrane right back to the dorsum of the 10th 

 abdominal segment, though some lines can be detected between the 

 dorsum of the 10th abdominal and what are probably the eminences 

 of the venter of the 9th abdominal segment. There is, on the extreme 

 dorsum, a trace of the suture between the 9th and 10th abdominal 

 segments. The cremastral hooks cover, as on a great continuous horse- 

 shoe, the whole area surrounding the thin membrane referred to. The 

 hooks are less than 0*1 mm. long, with a hook on each side of the 

 tip (anchor-shaped), and may number 500 or 600. Like the 

 other Theclids, the spiracles of the 7th and of 8th abdominal segments 

 are both obsolete (Chapman). Freyer notes the pupa as being 

 very different from that of the other "hairstreaks," since it has edges 

 and points, whilst the pupas of all the other species are smooth and 

 more rounded. Wilde gives a figure of the pupa in his Syst. Besch., 

 pi. viii., fig. 1. 



Dehiscence or pupa. — The dehiscence is along the usual Theclid 

 lines ; a slit down the thoracic dorsum, and one separating the 

 head and antennas from the prothorax and a portion of the wings ; 

 the metathorax may separate from the 1st abdominal segment, 

 and other incisions break down easily in the empty pupa- 

 case. Towards their middle and onwards, however, the antennaa 

 may adhere to the wings, and, holding the face-parts in position, the 

 valves, so formed as to allow the butterfly to escape, usually spring back 

 into place, so that an empty pupa-case is very similar to a living one. 

 As regards free segments, all the abdominal incisions from the 1st to 

 the 8th abdominal segments (not 8th to 9th) open easily in the 

 empty pupa-case, showing an intersegmental membrane, the lst-4th 

 abdominal, however, only dorsally, and the wings seem to have some 

 adherence to the 5th abdominal segment in some pupae. Probably all, 

 or some of these, open a little in dehiscence, but it is not clear that 

 movement takes place in any of them in the living pupa. 



Time of appearance. — As this species extends neither to very 

 high nor low latitudes, nor to high altitudes, we find comparatively 

 little range in the time of its appearance, such variation as is found 

 being largely due to the difference of the seasons in its special locality. 

 In England, its average time may be said to be between June 20th and 



