74 [September, 



is of a dull black colour, with greenish mouth ; the body velvety -black, 

 with a dingy olive-greenish plate on the second segment, having a wide 

 black dorsal division ; on the other segments, are olivaceous greenish- 

 yellow tubercular warts, each anterior pair on the back being distinctly 

 larger than the others, which are very minute, all bearing a few weak 

 soft yellowish hairs ; a black dorsal blunt projection is on the twelfth 

 segment ; the anal plate and outer sides of the anal legs are pale olive- 

 greenish-yellow ; the ventral legs are blackish on the outside with 

 greenish innerside, the anterior legs olivaceous yellow and shining. 

 From the first, they at intervals fed on two particular leaves near the 

 top of the birch spray whereon they had all assembled, holding 

 to the twig by their ventral and anal legs only, the fore-part of each 

 body being bent back away from the twig, leaving the anterior legs 

 free ; by the fourth day, their colouring had become dingy blackish- 

 olive, with the mouth orange-ochreous, a blackish dorsal line, black 

 tubercular spots, a conical hump on the twelfth segment, a faintly paler 

 spiracular ridge on the thoracic region, and the anterior legs pale 

 oi'ange, with black bases. 



After the first moult, the ground-colour is of a subdued green, 

 thickly freckled with black atoms ; the head and plate on second 

 segment paler, of sober greenish-yellow, as are also the spiracular 

 ridge on the thoracic segments, and a green backward-slanting stripe 

 on the side of each of the others, and this is still paler and yellower 

 on the eleventh and the twelfth, on which last a stripe begins at the 

 top of the blunt eminence ; the anal flap is margined with the same 

 colour ; the head is marked with two black stripes on either side ; a 

 black dorsal line divides the front plate, and continues throughout 

 over the hump as far as the anal flap. 



After the second moult, they were an inch long, and then broke 

 up their society and separated for independent existence, yet were 

 sufficiently amiable, whenever they chanced to find themselves near 

 each other, to agree perfectly well at any time ; while resting, they 

 still elevated the front part of their bodies as when younger ; at this 

 stage, the colour of the back is much lighter green, the dorsal line 

 dark green, except at the apex of the hump, where it is black ; the 

 sides are of a fuller green finely dotted with black ; on the back, the 

 dots show greenish, though they have become nearly obsolete there ; 

 the stripes on the head are alternately whitish-yellow and dark green, 

 and on the thoracic segments the whitish spiracular ridge is conspicuous, 

 as also on the other segments are the side stripes of yellowish-white 

 bordered above with deep green, and these also now not only reach 



