MALACOSOMA. 527 



certainty to the larva? and bred moths. He illustrates his contention 

 by means of M. calif ornica, which inhabits the coast region of 

 California and the Pacific north-west, and which, he states, is made 

 into three species by Dyar on larval peculiarities, viz. : — 



(1) A dorsal pale line, sometimes obsolete : 



Lateral blue region heavily shaded . . . . . . ambisimilis. 



Lateral region with no blue shade . . . . . . californica. 



(2) A dorsal row of elliptical blue spots . . .. .. .. pluvialis. 



We are not in a position to question the specific identity or distinct- 

 ness of these insects, but we mention the subject here because of the 

 importance of fully allowing for larval variation, which is somewhat ex- 

 tensive in this and allied genera. The solitary habit appears to be adopted 

 by the larva? of all the species in the last stadium. The European species 

 that feed on low plants, J\[. castrensis, M. alpicola, &c, still keep up 

 the gregarious habit, and construct silken streets. On the high Alps, that 

 form the habitat of the latter species, at from 6000ft. -7000ft. elevation, 

 the silken paths may be observed in the grass, the dewdrops on them 

 glittering in the sun, and by following them up one readily finds the 

 community, for although living solitarily in their last instar they rarely 

 spread to the extent that the tree- and shrub-feeding species appear to 

 do. It is very interesting to watch the movement of the full-grown 

 larva of M. alpicola, for it alternately hides and exposes a narrow zone 

 between the segment's, the anterior segment sliding backwards over it, 

 and this small portion is bounded on each side by rows of minute 

 glistening white points at the bottom of fine sulci. The neuiij hatched 

 larva shows many generalised characters, i much larger than ii, the 

 latter bearing as a rule only two small chitinous-based seta?, iii forms 

 a single-haired chitinous-based tubercle, whilst iv and v are represented 

 by a double generalised tubercle bearing two seta?; the hairs are usually 

 serrated, the head blackish and shiny. The principal characters of 

 the Malacosomid larva (specially noted from M. alpicola), are: The head 

 only just less than the prothorax, covered with short hairs, an 

 aggregation of minute black spots on the head, some variation in the 

 number of ocelli (of which there are six normally, but may be only 

 four) ; the marked spinneret ; the prolegs consist of two large basal 

 rings of soft tissue, and then a long extensile segment carrying a 

 row of about 24 strong brown hooks ; the development of the prothoracic 

 "ear-tubercles ;" the longitudinal disposition of the lines. The larva 

 is clothed with hairs but not sufficiently dense to obscure the tint of 

 the larval skin which gives the larva its colour, and it appears 

 impossible to trace the tubercles in a full-grown larva. There is a 

 moderately well -developed marginal flange which, at the anterior 

 portion of each segment, rises considerably above the level of the 

 spiracles. The anal plate is well-defined (blue in alpicola). The 

 Malacosomid cocoon is thin and papery in texture, usually well inter- 

 mixed with yellow particles of aragonite, secreted by the Malpighian 

 tubules and plastered on the inside of the walls, badly fed or starved 

 larva? spinning white cocoons without the characteristic colouring 

 matter distributed through them. This material gives a peculiar appear- 

 ance to the pupa, for the fine yellow powder appears to be loosened by 

 the movement of the pupa, and to be spread over the latter, collecting, 

 however, more thickly where the hairs are strongest and most 

 numerous. This appearance is only to be equalled by that of certain 



