112 



BRITISH BUTTERFLIES. 



of a bulb; this portion is also of much slighter texture than the bulb in 

 Agriades, which is a dense and highly cbitinised structure. Based on 

 this character, Polyommatus would comprise amor, Stand., candalus, 

 H.-Sch., eelina, Aust., eros, Ochs., hunza, Gr.-Gr., martini, All., 

 meleager, Esp., psylorita, Frr., sarta, Alph., renus, Stand., icarus, v. 

 Rott. (with its many forms — persica, Butl., icadius, Gr.-Gr., etc.). 



The egg of Polyomwatus is very characteristically Lycaenid in form 

 and general appearance, but differs considerably from the much more 

 specialised Agriadid egg with its flattened top, high and large 

 marginal cells, and widely-opened lateral cells. * In Polyommatus the 

 cells of the upper surface are more like those of the sides, the pillars 

 and knobs at the angles of the reticulation, commencing before, and 

 not directly at, the margin, as in Agriades. 



The larvae of Polyommatus (icarus) and Agriades (coridon and 

 thetis) are very similar when young, but certain differences become 

 marked by the time the third (hybernating) instar is reached. 

 The most marked differences are in the character of the hairs 

 and the hairbases. In the case of Polyommatus it is difficult to be 

 sure that the hair-base is other than perfectly smooth, whereas, in 

 Agriades (as already noted), the hairbases are of a markedly stellate 

 character ; the development of stellate points to the hairbases 

 is, however, to be noted on the thorax (prothoracic plate), and 

 along the posterior margin of the segments, but even then to 

 nothing like the degree noticeable in Agriades. In the last instar 

 there is also a marked difference in the hairs themselves, those of 

 Polyommatus (icarus) being (broadly) straight, smooth, and tapered, 

 whilst in Agriades they develop into all sorts of short, curved (even 

 recurved), clubbed and rough (spiculated) forms, e.g., on the 7th 

 abdominal segment (on which the honey-gland is situated), the hairs 

 in Agriades are short, clubbed or fungiform in A. coridon, and more bent, 

 almost hooked in A. thetis, whilst, in Polyounnatus, they are much fewer 

 in number, and the extreme forms near the gland are blunt -ended, 

 and of nearly equal thickness throughout, not extremely short, but 

 many of them curved through nearly a right angle ; the blunt end and 

 this bend are, in fact, all that the hairs here do to assume the curious 

 forms, apparently most abundant near the honey-gland in so many 

 larvae of " blues," etc. In Polyommatus (icarus), also, one finds between 

 the honey-gland and the spiracle, three fairly long hairs (of group iii), 

 of which nothing is seen in A. coridon or A. thetis (Chapman). 



The pupa of Polyommatus (icarus), though very similar to Agriades 

 (coridon and thetis) in its apparent smoothness, want of cremastral 

 hooks, etc., is \evy different in the structure of its hairs, which, 

 simple or slightly clubbed in Agriades, are more strongly clubbed, the 

 clubs with well-developed spicules, in Polyommatus. The larva makes 

 a weak sort of cocoon, which acts to some extent as a support, but 

 it does not appear to enter the ground as does the larva of Agriades. 



The sexual dimorphism in the genus Polyounnatus is most marked, 

 the $ s blue in colour, the $ s brown, usually with more or less well- 

 developed submarginal lunules, although, in some species, the 2 s are 



* The egg of A. thetis is described (preceding vol., pp. 359-60) as having cells 

 , 04mm. across; they are much larger than those of P. icarus, and the measure- 

 ment is a misprint for 007mm. Those of P. icarus are 0*04mm., of Apriades 

 thetis larger, viz., 0-07mm. 



