ON THE LARVA UV AKCTlA (AIA. 35 



skin, in wliicli skin the larvfe liybernate, nevertheless, both the Forward 

 and Laggard forms do occur not uncommonly, and it is not perhaps 

 unfair to assume that the various intermediate forms met with in my 

 exj)eriments also occur, though very rarely. 



DESCKIPTION OF PLATE I. 



All Figures amplified x 2. 

 Hybernating form in oth skin ; resembles Laggards. 

 Hybernating form in (Uh skin ; plumage resembles red form 



met with in Brood 1. 

 Laggard in 5th skin. 

 Ordinary form, 6th skin ; caia plumage. 

 Hybernating form, 6tli skin, long whitish hairs; raia-liko 



jilumage. 

 Laggard, in Gth skin. 

 Forward, 4th skin. 

 Normal, 4th skin. 



NOTES ON PLATE I. 



1 may remark, in connection with the jilates, that perhaps of all 

 larva?, that of caia is the most difficult to figure satisfactorily. Buckler's 

 attempts to do so were far from successful ; these, however, were made 

 in the earlier years of his work on larvaa, and he would, no doulit, had 

 he attempted it, have l)een more successful later. In view of this 

 difficulty, acknowledged by such a master as Buckler, and of the further 

 fact, that wliat have to be shown on my plates are variations in length, 

 colour and density oi plumage without any structural difference, I 

 think Mr. Knight is to be congratulated on his successful delineations 

 and on their reproductions in the plates, which are not so far behind 

 the original drawings as sometimes happens. Fig. 8 represents a 

 Normal larva in the 4th skin, i.e., the last stage with Spilosotiid 

 plumage ; whilst fig. 7 represents the same stage, 4th skin, of 

 a Forward larva, but an unusually dark form, in Avhicli the lateral 

 yellow line is reduced to one set only of the diagonal daslies, of 

 which in its most definite development it consists ; frecpiently in tliis 

 stage the Forward is even })aler than the Normal form. Tliese two 

 are from larvaj of the 4th brood. Fig. 4 is a Normal in Gth skin that 

 in which it assumes caid plumage. 



Figs. 1, 2 and 5 (with fig. 4, Plate II.) represent various forms of 

 hybernating larvae (Normals) ; I have already commented on fig. 2. 

 Fig. 1 is in 5th skin, and is a variety that, by its smaller size, shorter 

 liairs, and very definite lateral line, more resembles some forms of Lag- 

 gards than Normal hybernators. Fig. 5, on the other hand, lias various 

 long white hairs, and is of a darker colour ; it makes a distinct approacli 

 to caia plumage, and is in Gth skin. Fig. 4, Plate II., exce})t tliat it is 

 rather dark, or rather that tlie dark skin is too distinctly represented in 

 the drawing, and overpowers the effect of the ^^aler ])lumage, is a Nor- 

 mal h3d3ernating larva in 5th skin. 



Fig. 3 is a Laggard in 5th skin ; compare for size with Normal in 

 4th skin (Fig. 8). 



Fig. G is a Laggard in Gth skin, smaller tlian a normal liybernator 

 in 5th skin ; it is rather larger and darker than most Laggards at this 

 stage, and has no lateral line. 



{To be continued). 



