158 Mr. E. B. Poulton. Colour-relation between the [Feb. 4, 



August 16th. — Upon 8. rubra by the Cherwell (as above), one nearly- 

 adult bright yellowish larva. Also upon S. cinerea in the same 

 locality two nearly adult larvae (on the same bush), of which one was 

 slightly on the whitish side of an intermediate variety, while the 

 other was a rather bright yellowish variety. Also upon 8. triandra 

 in the same locality one almost full-fed bright yellowish larva. 



August 23rd. — Upon 8. Smithiana at Binsey upon the Isis, near 

 Oxford, one nearly adult larva on the whitish side of an intermediate 

 variety. Also upon 8. triandra in the same locality, one nearly adult 

 bright yellowish variety. Also upon 8. triandra upon the Isis at 

 Medley Weir near Oxford, one bright yellowish larva which had just 

 entered the last stage. 



August 25th. — Upon S. rubra (Cherwell) three small larvae towards 

 the end of the third stage, all strongly yellowish varieties, but differ- 

 ing somewhat in intensity. 



August 30th. — Upon 8. triandra close to the bridge at Ferry 

 Hincksey, near Oxford, one nearly adult larva which was a good 

 yellowish variety, but rather whitish on the back. Also upon ordinary 

 apple in a garden at Oxford one very white variety at the end of the 

 fourth stage (changing its skin). 



September 11th and 12th. — Upon a variety of S. alba with small 

 narrow leaves, having smooth greenish under sides ; in a dry part of 

 the bed of the river at Visp, Switzerland, two full-fed strong yellow 

 varieties (although not the strongest because of the want of a distinct 

 yellow tinge to the under surface) . Both had the very sharply marked 

 and distinct white stripes which are often found on larvae with this tint 

 of ground-colour. Also September 12th, near the stream which flows 

 through Brigue, Switzerland, three larvae upon different species of 

 sallow. Upon a variety of S. alba very similar to the above ( ? S. 

 vitellina), an adult intermediate variety rather strongly tending 

 towards the yellowish form upon its dorsal surface, and having very 

 distinct white stripes, such as were possessed by the larvae from Visp. 

 Upon 8. incana, a yellow variety of the larva, looking as though it 

 would have been very yellow if it had been in a healthy condition. 

 But the larva, which was well in the last stage, was much stunted and 

 in very bad health, having been attacked probably by some parasite, 

 and pierced in twenty-eight places. Also upon 8. alba (the leaves 

 much like the common English form), a larva which was advanced in 

 the last stage, and an exceedingly white variety — the palest I have 

 ever seen. There was a little yellow on the under side, but it was 

 not at all the tint of the yellowish varieties, and indicated no transition 

 in that direction. The larva did not seem to be very healthy. It 

 possessed in common with all very strong white varieties a distinct 

 trace of the subdorsal line for its whole length, and there was a trace 

 of the darkening for a border to a " ninth stripe " upon the third 



