264 



Transactions. 



Larvae. 



Head (fig. D) : Bezzi (1914, pp. 119, 122, 123) describes the colour- 

 scheme of the frontal spot on all three larvae. The frontal spot is a special 

 plate forming the dorsal prominence of the cephalon. It is subquadrate, 

 rounded posteriorly, the lateral portions separated from the remainder of 

 the segment by well-defined connecting membrane. In the centre lies a 

 definite separate elliptical plate, placed longitudinally, tapering sharply at 

 the ends, and suggesting some relation to the process of pupation, or 

 moulting stages of the larvae (fig. 125). 



Dorsal armature (figs. 1 to 37) : In addition to the primary spiny 

 armature, all three larvae bear numerous spines, ranging from a minute 

 single hair, or a group of single hairs (palmate), through the type of cone 

 or double cone, up to the many varied types of fan-shaped spines. 

 A study of these spines strongly suggests an evolutionary series. The 

 largest fan spines range themselves in rows near the anterior margins of the 

 segments and form groups near the base of the lateral processess. Each 



Fig. D. — Cephalon (diagrammatic) of larva. 1. (Dorsal) showing central plate. 

 2. (Ventral) showing mouth-parts. 3 (Ventral) showing relation of dorsal 

 and ventral portions. 



segment has also many special flat cells or groups of cells scattered over 

 the dorsum (figs 117 to 121), and these also are arranged in rows near the 

 outer portion of the anterior margins of the segments. Larva B has a 

 thickly-scattered armature of transparent fan spines, and these approxi- 

 mate so closely to the main armature in size in many cases that it is 

 difficult to pick out the cones from the fans (fig. 119). The integument on 

 all three larvae shows a well-defined zigzag appearance. At the margins of 

 the segments this resolves into the scale-like minute processes of the integu- 

 ment (fig. 120). A view along the margin shows them V-shaped or 

 W-shaped like the teeth of a saw. In B. johannis the scale processes 

 have a minute terminal spine. I can detect no terminal spine on these 

 processes in the Blepharocerid larvae. The three types of lateral processes 

 (figs. 38 to 40) are distinct in their form and in the type of the spines 

 or hairs connected with each. 



Posterior marginal spines (figs. 41 to 43) : Larva A averages 40 spines in 

 a double row laterally, merging to a single row towards the centre of the 

 margin. Larva B has about 30 spines in a single row, as also has larva C. 



