[ 105] 



The fully grown Larva : External features. 



Owing to the difficulty of keeping alive recently emerged larvae which 

 were prevented from burrowing into the soil, it has not been possible so 

 far to follow the changes in external form effected at the various moults. 

 The larva when fully grown attains at fiill extension a length of about 

 40 mm. It is now of a brownish-grey earthy colour interspersed with 

 irregularly placed blackish dots. Frequently the longitudinal tracheal 

 trunks, two in number, may be seen through the skin. The shape is 

 cylindrical, slightly narrowed anteriorly, and expanded posteriorly into 

 a peristigmatic papillae-bearing area. The skin, which is generally 

 tense in healthy larvae, exhibits the following characteristics: — along 

 each side there is a moderately wide strip which on the animal 

 contracting folds outward, forming a pair of blunt keel-like longi- 

 tudinal ridges. Besides numerous transverse wrinklings, there are 

 slight but definite transverse furrows marking off distinct segments. 

 Eleven of these can generally be counted. Each segment bears on 

 its ventral surface four very minute bristles, two lateral and two near 

 the middle line slightly in front of the lateral pair. On the first four 

 segments behind the head dorsally, there is a row of bristles, and a pair 

 of dorso-lateral bristles on succeeding segments. The head bears a 

 pair of short jointed antennae; there is a very strong chitinous and 

 highly complex mouth armature which includes massive toothed 

 mandibles with palps, a pair of serrated first maxillae, notched 

 united second maxillae and elaborately folded and bristled labrum 

 (Plate XIX (a)). The whole set of structures is based upon a large 

 strong bivalved chitinous support which surrounds the gullet. 



The anus, which is sub-terminal, is surrounded by large fleshy 

 lobes and a pair of large retractile laterally placed conical papillae. 

 Beling regards these papillae as characteristic for this species. 



On the somewhat truncated terminal region there is a pair of large 

 brown coloured circular stigmata, each with a lighter glistening dull golden 

 marginal ring. This stigmatic area is expanded on its border into six 

 conical papillae, of definite form and arrangement. There is a ventral 

 pair whose tips are black with a clear central area. This pair appears 

 to have a sensory function, and may be seen at times in the living 

 animal apposed to the stigmata above. Below each of these ventral 

 papillae there is a pair of small pigmented spots which are some- 

 times united to form a short streak on each side. The remaining 



