410 BRITISH LEPIDOPTERA. 



of stripes least strongly marked ; shagreen points maintain yellow colour 

 even in red areas ; the colours dull before pupation (Bacot). The young 

 larva, before its first moult, has the head rounded, the subdivisions of 

 the segments already marked, the skin covered with small two- 

 pronged hairs, not so conspicuous as those of S. ocellata and 

 A. populi, the horn 2mm. in length, black, thickly set with short 

 two-pointed bristles, its end with two points ; the colour yellowish- 

 green, more full green on the back ; the figure is slender. The 

 first moult takes place when the larva is about nmm. long; the 

 horn becomes 3mm. long ; yellowish in colour, with dark short 

 spines; the lobes of the head become pointed, with yellow tips, 

 the eight subdivisions of each segment set with rough points * ; 

 the colour yellowish-green, and the seven yellow lateral stripes 

 slanting appear plainly. The second moult comes when the larva 

 is about 1 8mm. long ; the tips of the lobes of the head become 

 reddish, the rough points on the skin yellowish. The third moult 

 finds the larva about 25mm. long and the yellow scutcheon on 

 the thirteenth segment appears. The fourth moult is passed 

 when the larva is about 35mm. long; up to this time the figure 

 has been very much more slender than that of S. ocellata or A. 

 populi, but now it begins to grow stouter. The biggest larva 

 I had this summer grew to be something less than 50mm. in 

 length, stout, but tapering forwards a good deal, the skin smooth, 

 the dots remain but are not rough; the face triangular, the horn 

 short and rough, a rough oblong patch on the anal flap ; the 

 back light yellow-green, the belly duller green, the dots above 

 the spiracles yellow, below them whitish ; the face glaucous- 

 green, slightly dotted with white, the lobes broadly bordered 

 with opaque white outside, tips of the lobes slightly reddish ; 

 the seven slanting lateral stripes are pale yellow, edged in front 

 with bright green, six of them begin just at the level of the 

 spiracles, but the seventh is longer and goes through segments 11 

 and 12 running up to the horn. As the larva matures there 

 comes a red tinge in these stripes ; the horn is blue above and 

 red with yellow dots, below ; the rough spots on the anal flap 

 are red edged with deep yellow ; the spiracles are yellowish-white 

 broadly ringed with red ; the thoracic legs pale yellowish ringed with 

 delicate pink, the ventral and anal prolegs coloured like the belly (Hellins). 

 Variation of larva. — The fullgrown larva? of M. tiliae vary 

 a good deal in coloration. Some of mine had red blotches bordering 

 the front of the stripes ; one or two had red borders to all the 

 stripes, others only to some of them. I particularly noticed that 

 the weak stripe (the 6th) always came off worst, the blotch being 

 either faint or altogether absent from this stripe, even when it was 

 strongly marked on all the others. Another thing that struck me 

 was that the colour of the tubercles persisted more than that of 

 the surrounding surface, the yellow colour showing up plainly in 

 the midst of the red blotches. It is probable that these red blotches 



* Reaumur first applied (Mem., i., p. 77) the term " shagreened " to the rough 

 skin of this and the allied species. He writes : " Leur peau peut £tre comparee a 

 celle du chien do mer, et le nom qui semble le mieux leur convenir est celui de 

 chenilles chagrinees." He says that the rough points are arranged with method, are 

 coarse to the touch, formed of corneous matter, appearing under a microscope as tiny 

 " mamelons " springing from a circular base. 



