28 



in C. Pusio, the supra- and sub-cesophageal ganglia occupy the greater 

 part of the first segment. The large brain is naturally associated with 

 the high psychical life of the insect. Only one larva among those 

 described in the appendix was found to have the brain situated within 

 the head, and in this case the brain was very small, and the head 

 exceptionally large. 



THE FIRST INSTAR. 



The larva in its first instar or before its first moult is exceedingly 

 transparent, save for a mass of greenish-yellow yolk cells, which still 

 occupy the body cavity. The head is at first transparent but by the 

 third or fourth day is quite dark. The blood is quite transparent 

 and remains so for many weeks. The nervous system is very large 

 in comparision with the size of the insect, especially the brain, which 

 occupies the whole of segment i, a large part of segment 2, and also 

 projects some way into the head cavity. The fusion of the last two 

 abdominal ganglia is incomplete. The tracheae are not visible, and if 

 present contain no air. The processes of the labrum seem to form 

 a less complete apparatus, fewer parts being visible. The hairs 

 distributed over the body are slightly different, but the chief point 

 is that the bifurcators are entirely absent, and in their place are found 

 very minute simple hairs. Each anal sense organ contains only four 

 setae ; the fat-sacs are present but very small. 



Length of larva '32 mm. 



Diameter of head '04 mm. 



Diameter of sensory bulb '003 mm. 



THE PREPUPAL LARVA. 



When the larva is full grown and about to change into a pupa 

 certain changes take place in its appearance. The thoracic segments 

 become very distended, the body becomes more opaque and redder 

 in colour, but not nearly so red as in the blood-worm. The fatty 

 tissue gets very dense and massive, hiding the internal organs from 



