Plate XXV. 

 (To be bound facing Plate XXV.) 

 Structural details of larva of Celastrina argiolus. 



Fig. 1. — Prothoracic plate of Celastrina argiolus in penultimate in star x 150. 



-The plate is outlined by folds, into which the skin around it has fallen in its 

 preparation, the plate differing only from the surrounding slun by its greater density, 

 and being indistinguishable therefrom in colour, armature of hairs, etc., except for 

 a pair of hairs towards posterior border and outer angles (shown in fig. as two con- 

 spicuously dark circles, which are really bases of the hairs, and are round, smooth, 

 large, and dark in colour, differing in these respects from any other hair-bases of the 

 larva). The hairs themselves, which do not come out in the fig., are very long, flow- 

 ing, slender, nearly uniform in thickness from end to end, and quite smooth and 

 unspiculated, again quite unlike any other hair the larva possesses. These special 

 hairs are most easily observed in penultimate skin. Little traces appear to have been 

 noticed in larvae of Chrysophanids and Ruralids (but are present in Bithys quercus). 

 They appear, however, to be present in all Lycaenine larvae, e.g., Lampides boelicus , 

 Langia telicanus, Polyommatus icarus, Agriades bellargus, A. corydon, etc. ; in 

 larva of L. telicanus especially conspicuous ; in A. bellargus and A. corydon they 

 are the centre of, but are somewhat lost in, a dark spot at the outer angle of 

 prothoracic plate. 



Fig. 2. — Portion of larval skin of Celastrina argiolus in last instar x 150 (see 

 also pi. xxvi., fig. 2). 



Taken from near the dorsal margin of a segment. The longest hairs are 

 those of dorsal crest (setae of tubercles i and ii), the others are the very numerous 

 skin-hairs. In spite of the crowding of hairs (and blurring due to reproduction), 

 it shows the special character of these hairs as compared with stage 1 (pi. xxiii.), 

 stage 2 (pi. xxiv.), and previous skin (pi. xxvi., fig. 1). 



