on colour-relation. 241 



sides of the larva corresponded. The thoracic legs were 

 faintly red ; there was no red on the claspers. The other 

 characters were all as in the first larva. There was no 

 eighth stripe. The third larva developed an upper row 

 of seven spots, one anterior to each stripe, viz., on ahdo- 

 minal segments 1—8. The third and seventh spots 

 occupied four rings, the first two rings, and the rest 

 three rings ; nevertheless, the third, fourth, and fifth 

 spots were the largest, hecause longer vertically than the 

 others. All the spots were larger and more conspicuous 

 than in the second larva, also deeper red. The sides 

 corresponded. All other characters were just as in the 

 first larva. 



Sept. 9th. — The fourth ecdysis of the fourth larva took 

 place. It developed an upper row of six spots, one in 

 front of the first, second, third, fourth, fifth, and seventh 

 stripes, viz., on abdominal segments one, two, three, 

 four, five, and seven. The spot in front of the first stripe 

 (on first abdominal segment) was the smallest, occupying 

 two rings ; the others each occupied three rings. Other 

 characters as in the first larva. 



Sept. 10th. — The upper row of spots in the first larva 

 increased in width ; the third, fourth, and fifth spots (on 

 abdominal segments one, two, and three) now covered 

 four rings. This increase in the width of spots did not 

 happen in any other larvae. 



Sept. 25th. — The first larva pupated. 



Sept. 27th. — The second, third, and fourth larvae 

 pupated. The larva figured (PI. XL, fig. 8) is the first. 



Smerintlius populi. 



On August 8th, 1890, 1 captured a red-spotted larva of 

 S. populi in the fourth stage on poplar. 



Aug 12th. — I drew (PL XL, fig. 11) abdominal seg- 

 ments five and six to show the spots. There were two 

 rows of spots, of ten each, the upper row being the 

 largest. The upper row were placed one anterior to each 

 oblique stripe, and four extra to these placed irregularly 

 towards the head. The lower (spiracular) row were 

 placed one posterior to each stripe, two extra on the last 

 segment, and one extra towards the head. The spots in 

 both rows were irregular and roundish. 



Aug. 19th. — A change took place in the spiracular 

 spots without any moult. The lower row became like 



