348 Transactions. — Zoology. 



head yellowish with a suspicion of mottling. The mouth-parts 

 are normal, not protruding as in previous stage ; spinneret is 

 short and stout. Pro thorax as previous stage. Mesothorax : 

 One below the other are two setae in a dorsal depression, below 

 which a large swelling bears two similar setae, a lower posterior 

 swelling bears one seta, an anterior swelling bears two setae ; 

 tubercle above legs bears two setae. Abdominal segments : All 

 tubercles bear single seta, i. and ii. normal, iii. above the spi- 

 racle, which is well sunk into a lateral depression, anterior 

 subspiracular almost below spiracle, post-subspiracular quite 

 beneath, vi. anterior, basal setae three ii: number. Abdominal 

 feet have a single row of closely placed terminal hooks. 



The adult larva is semitransparent green, with no appreciable 

 markings except on the head, which is yellowish with character- 

 istic brown mottling on each lobe. External structure as in 

 second stage. 



The length of a larva at fifteen days is 10 mm., after which 

 it grows rapidly ; at thirty days it is 28 mm., remaining attenu- 

 ated in breadth. Duration of larval existence, thirty to thirtv- 

 two days. 



The skin has a reticulation. From the centre of each figure — 

 hexagonal or what not — of which it is composed a small boss 

 rises tipped with a spike : these spicules persist throughout the 

 larval existence, and practically cover the whole skin ; but 

 around the base of setae a space exists without the spicules. 

 The anal comb is seen with difficulty in a newly hatched larva, 

 when the prongs are like seta:. In an adult larva (figs. 15 and 16) 

 the comb consists of eight strong prongs each terminating in 

 two points ; at either side are incipient prongs. The pr< 

 rise from a small pad on the underside of anal flap. Judging 

 from the direction of the prongs in different specimens examined, 

 the comb may be elevated or lowered at will. The function of 

 the comb is probably in connection with the removal of excre- 

 ment, and the position of comb is best seen when the anal flap 

 is distended at the passing of same. Spicules are numerous in 

 the region of the comb. 



I once found three pupae each in a leaf of Urtica ferox (tree- 

 nettle). These leaves are covered with stinging spines, and had 

 been rolled into a cylinder. It is doubtful whether the larva 1 

 fed on the Urtica leaves. 



The pupal shroud is made by the larva firsl with an outer 

 series of silk threads apparently placed irregularly, but designed 

 to hold together the two leaves or the told of the leaf and pre- 

 vent any alteration in the curvature which might subsequently 

 affect the pupa disadvantagoously. Within this outer series 

 oi threads a definite closely woven elongate cocoon is made 



