76 BRITISH BUTTERFLIES. 



thorax. The most pronounced difference is in the greater number of 

 hairs in A. coridon, their slightly greater length and their having more 

 uniformly their terminal portions dark in colour, e.g., round the 

 spiracle of the 2nd abdominal segment there are 12 to 15 hairs in A. 

 thetis, 40 to 50 in A. coridon, and extending to the margins of the 

 segment instead of merely in the spiracular area. The other segments 

 present similar differences. This character would readily serve to 

 distinguish the two pupae, were it not for the difficulty of counting the 

 hairs in a living or mounted specimen. On the ventral aspect, the 

 hairs on the 5th and 6th abdominal segments on' what one. may call 

 the proleg region, are twice as numerous and half as long again in A. 

 coridon as in A. thetis. In both species this area presents another point 

 of interest. In the undisturbed pupa the ends of the antennae abut 

 against the margin of the 5th abdominal segment, no trace of the 

 maxillae appearing, but, when this portion of the pupa is more closely 

 examined after making it transparent on a slide, it is seen that the 

 maxillae have here a small portion so far chitinised that one would 

 expect to find them exposed externally, though this- is not so, and that 

 a further portion (about 0-6mm.) passes into the sheath (in inter- 

 segmental membrane) behind the 5th abdominal segment; the anterior 

 margin of this segment is also folded inward and backward across the 

 whole front of the segment. Further, the 6th abdominal segment has 

 a large flap of similar form in both species, folded inwards and back- 

 wards from its front margin, either of the segment itself or of the 

 intersegmental tissue (if these are distinguishable otherwise than 

 functionally), and a very narrow strip is similarly folded in along the 

 front of the 7th abdominal segment ; this strip seems to be entirely in 

 the intersegmental membrane. The lenticles are, perhaps, rather larger 

 and more crowded in A. coridon in the spiracular region. In both we 

 have the scar-like smooth area with the skin-ribs around it arranged 

 in some degree in a radiating manner halfway between the dorsum 

 and sph'acles on the 3rd to 6th abdominal segments, and also, but less 

 obviously, on the 1st and 2nd abdominals, quite wanting on the 7th, 

 and corresponding with the " upholstered " hollows that exist at these 

 points in the larva. The scar of the honey-gland is very similar in 

 both pupae, and is visible in the living pupa or the empty shell to the 

 naked eye (Chapman). 



Temperature experiments on pup;e of Agriades coridon. — Krodel 

 records (AW/. Zeits. fur Ent., ix., p. 106) that he was only able to 

 experiment with low (cold) temperatures. He found that the " critical 

 moment," i.e., that point when the chitinous skin of the pupa possesses 

 the necessary consistency to be able to endure without danger rapid 

 and extreme changes of temperature, and at the same time the pig- 

 ments respond to these changes and lead to an alteration of the wing- 

 markings, could he fixed at a- pupal age of li\e to six hours; younger pupae 

 die in the cold through the crushing of their chitinous skin, and after they 

 are six hours old, pupae give no aberrations. One must not, he says, allow 

 oneself to he deceived by the glassy appearance of the pupae and assume 

 that they are boo fresh lor the experiment, since the pupae of both Agriades 

 coridon and / lirsutina dam on possess the same transparent exterior 

 up bo the age of two or three days, which allows nearly all the 

 details of the enclosed future imago to be dearly perceived, just as 

 it appears Immediately after entering the pupal state. Krodel then 



