PLEBEIIDI. 



157 



it has a more special character in the hook of the dorsal process being folded at 

 the bend to about 170°, i.e., the base and upper part almost folded together. 



Albuiin*- As exemplified in pheretes, this group agrees with Ancia in tn» 

 general form of the long, hard process of the clasp, but has the hook of the dorsal 

 process with a very broad, square base, and the upper portion thick below, tapering, 

 and ending in a slight hook. . 



Latiorina • As exemplified bv orbit uhis and yyrenaica, this group is very near 

 Ubulina but the dorsal hook is less heavy, and more like that of Polyommatus 

 (icarus). ' The hard process of the clasp is rather long, and the serrate margin 

 extends round an almost circular termination.'- 



Agriades • As exemplified in coridon and thetts (bellargus), it is not so very 

 difficult to separate this horn Polyommatus {icarus), but, m other species that appear 

 to have to be divided between these groups, the separation is much more so. Inis 

 group exhibits a dorsal process with well-developed wing (as many others have, 

 though occasion to refer to it has not before arisen); the hook has a large, square 

 base from which the comparatively slender, rather S-shaped, curved, upper part, 

 arises at about a right angle, and ends opposite the middle of the dorsal process. 



Polyommatus : As exemplified in icarus, eros, etc., this group possesses a less 

 heaw base to the clasp, a less slender upper portion, and its curvature is simple. 

 In Polyommatus the hard process of the clasp is rather shorter than m Agriades. 

 In both there is a soft process between the two divisions of the clasp ; |rt oiten 

 swells out in preparation in a balloon-like way ;] whether we regard it as a part of 

 the soft process of the clasp, or a development of the membrane between the two 

 processes does not much matter, but its considerable development (it occurs else- 

 where) is characteristic of these two genera."' 



Chapman adds that, genitalically, our Hirsutina belongs strictly to 

 Polyommatus, the icarus group. It seems, however, such a natural 

 group in other respects, that one feels very constrained to treat it 

 separately. It is to be noted that ChUades (trochylus) is Plebend. 



A study of the material in the British Museum collection raises 

 many and'serious doubts as to whether the real evolutionary relation- 

 ship of the verv widely different species included in our genera of this 

 tribe, would not be more properly indicated by their treatment as 

 distinct tribes, but the genitalia give no indication in this direction, 

 and these difficulties must be left for future consideration. As here 

 treated, this huge tribe shows remarkable variations in all the details 

 relating to the habits and structure of the individuals included in its 

 separate sections, or genera, remarkably uniform, however, as a rule, 

 within the limits of each separate section. These details will be better 

 dealt with in full, however, in our account of each separate genus. 



We may merely note here that the Plebeiids are, in their larval 

 habits, possiblv the most generalised of all the Lycamids, feeding 

 usually on the leaves of low leguminous plants, and hybernating in 

 the third larval stadium, eating out, when young, little patches of the 

 cellular tissue of leaves, which they pierce with their tiny head, and 

 are able to scour with the long extensible prothorax, differing thus 

 markedly from the seed-eating larvae of the Lampidids, Celastrinids, 

 and Everids already considered. But there are many exceptions to 

 these general truths, for the larvae of the Ariciids— A ricia astrarche, 

 A. eumedon, etc., feed on Geraniaceae, etc., that of Vacciniina optilete on 

 Vaccinium, whilst Plebeius argus (aegon), P. drgyrognomon, Af/nades 

 coridon, etc., hybernate as eggs, or rather as fully-formed larvae inside 

 the egg-shell, and so on. 



* When Prunner named this species orbitulus, was he aware of this peculiarity 

 which separated this species (and its allies) from the rest of the Plebeuds?— T.A.C. 



