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BKITISH BUTTEKFLIES. 



along the posterior side of the segment. The lateral line is also paler. 

 The outlines and aspects of the colours and bosses are very variable, 

 according to the angle of observation, due to the essential colouring 

 having a site some way beneath the skin. Others are more coloured, 

 and a richly-coloured one is even handsomer than in second instar. 

 The back, seen from above, has a marking, outlined with rich yellow, 

 broad along the posterior margin of segment, but. narrowed in front, 

 the edge being oblique at an angle of 45°; down the centre of this is a 

 double, rich, dark olive, band divided by a pale mediodorsal line, and 

 there is a rich pink centre to the yellow extensions ; the lateral line is 

 dull yellow, and the olive above this is paler round the spiracles, but forms 

 a dark margin to the yellow dorsal marks (showing them up well), and 

 a darker band above the lateral line that is almost reddish. The pro- 

 thorax is almost entirely olive, and the last segments are less clearly 

 marked. The hairs are a ruddy brown, and add somewhat to the 

 colouring. On the paler larvae the brown hairs look nearly black by 

 contrast. I have only one richly-coloured larva as above noted, and 

 only one or two nearly green ; the rest just show the markings dis- 

 tinctly by variations of tint, being chiefly green, with a pale lateral 

 line, the darker markings of the dark larva having a greater or less 

 tendency to be olive. Fourth instar : The larva in this, its last, skin, 

 is much as in the third instar as to hairs and colouring ; even the 

 greenest show a faint yellow oblique line as outer margin of the yellow 

 zigzag band. [They eat the flowers of broom most voraciously, and 

 grow quickly.] A fullgrown one is 18mm. -20mm. long, 5mm. wide, 

 and4-5mm. high; the colouring and transparency of the subcutaneous 

 region make it difficult to observe the "cushioning" accurately, but 

 there seems to be a deeply depressed line, running from below the 

 spiracle, backwards, upwards, and forwards, the last portion not very 

 far from, if not coinciding with, the oblique yellow line. The pro- 

 thorax is still at a lower level than the mesothorax, which hangs over 

 it in a large fold or roll, and places the prothoracic plate in an angular 

 hollow, very similar to that of the larva of Thestor ball us at this stage. 

 The plate itself is a triangular piece, with a narrower prolongation from 

 the middle of thefront edge, about 1 -00mm. from back to front, and 0"7mm. 

 from side to side, pale pinkish-brown, with a median yellow line (May 20th, 

 1906) (Chapman). Final instar: 15'75mm. in length, gains nearly 

 3mm. when stretched out in walking ; thick in proportion, and some- 

 what onisciform in shape, flattened beneath ; the head very small and 

 retractile; pro- and mesothorax rounded above; the other segments to 

 the 6th abdominal, with a dorsal hollow, having an eminence on each 

 side of it, which slopes thence to the lateral ridge; the last three 

 segments rather flattened above. The ground colour bright yellowish 

 olive-green, the hollow of the back a darker full green, and down its 

 centre runs the pale olive-green dorsal line, which gradually widens and 

 suddenly contracts on each segment throughout its course, and becomes 

 dark on the last three segments, where it is bordered by a yellowish 

 stripe on each side ; from each eminence on the other segments, a 

 thick bright yellow streak slants backwards and downwards, bounded 

 beneath by an equally thick streak of deep full green, most intense at 

 its beginning on each segment ; the lateral ridge has a stripe of 

 yellow, beginning at the mesothorax, and running continuously round 

 the anal extremity ; parallel to this, and above the spiracles, is a faint 



