HYLES EUPHORBIA. 221 



segment carries a white spot on either side, the 10th consists merely 

 of the anal flap and prolegs. ? Fourth instar : [Larva moulted between 

 5 a.m. and 6 a.m. on August 12th, 1899.] The head, thorax, anal 

 plate, prolegs and caudal horn were entirely yellow directly after the 

 moult. By n a.m., the tip of the caudal horn, the head, and the 

 thoracic segments were considerably darkened, but the fuller dark 

 colour was not obtained till about 6 p.m., i.e., until some 12 hours 

 had elapsed. The larva exactly 75m. long in its old skin, was -9m. 

 directly after moulting, the head and caudal horn comparatively 

 large ; the skin wrinkled. Head bright yellow, with a black spot 

 on either side of crown ; the front edge of prothorax folded so 

 that the white skin, laterally, is homologous with the white pair 

 of spots on the succeeding segments (these two spots united on 

 mesothorax), the prothorax otherwise entirely black ; there is a 

 bright -yellow mediodorsal line including the base of the caudal 

 horn ; the first subsegment of each segment is black and contains 

 the two characteristic white spots ; the remainder of the body-surface 

 now covered with pale yellow and black reticulations (in the form 

 of black rings that include the pale ground-colour), whilst the 

 lateral area is yellower than the dorsal and subspiracular areas ; 

 the subspiracular flange (still broken) is bright yellow, the reticulated 

 area continued below the flange ventrally to the line of the prolegs, 

 which are still yellow, and bear a dark plate externally • the 9th and 

 10th abdominal segments appear to have separate spots, whilst 

 the strong anal prolegs are yellow with external black plates ; ventrally, 

 the larva is greenish, with black spots between prolegs (also present 

 on abdominal segments 7 and 8) very marked, whilst the characteristic 

 reticulation of dorsum and sides is continued on the venter of the 

 1 st and 2nd abdominals; the white spots of the reticulation, directly 

 below the flange on the thoracic segments, form a sort of secondary 

 inferior flange above the black legs ; the caudal horn still black, 

 the tip blunter. The larva grows to i^ins. or 17 5 ins. in this stadium. 

 ? Fifth instar (newly-moulted) : [When the larvae first enter this instar 

 some three forms are observable ; as they become fullfed, the propor- 

 tion of the various colours changes and there are finally scarcely two 

 specimens alike. At the commencement of this instar they are 

 about ijins. long but they feed up rapidly and quickly, and reach 

 a length of from 3ms. to 4ms.] (1) Ground-colour green, the 

 spots on the crown of the head reduced ; the prothorax green, large 

 in proportion to size of head, the black reduced to a lateral mark 

 containing the white spots (united), as on the succeeding segments ; 

 the true legs yellow with black hooks ; the segmental incisions green ; 

 the reticulation fails in part, so that, laterally, a square spot of the 

 ground-colour is left on each segment between the white spots and 

 incision behind ; the dark colouring of the plates on the outside of the 

 prolegs (anal included) is wanting ; the caudal horn with a blunt 

 tip. (2) Much more intensely coloured; the head orange-yellow with 

 a black edge separating it from the mouth ; the black much increased 

 on the front of each segment ; the mediodorsal line deep orange- 

 yellow as also is the caudal horn, except the tip; the whole of the 

 segments closely reticulated ; the yellow lateral spots (described in the 

 preceding larva) deep orange, but more or less included in the ground- 

 colour; the lateral flange is deep yellow, but the true legs, prolegs, 



