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primitive form of Euchloe we have, since the larva, which I 

 have been fortunate in discovering this year, is ahnost exactly 

 like that of Pieris protodice, Bd. and Lee, a species which flies 

 in the same locality and lays its eggs on the flower-heads of 

 the same plants. Indeed, I sent Mr. W. H. Edwards a 

 number of larvae which were supposed to be those oi protodice, 

 from which he got pupae oi protodice, sure enough, but also a 

 pupa of aiisonides! And he wrote me that he had not noticed 

 any difference in the larvae, except that he sometimes thought 

 some were blacker — had more black hairs. This interesting 

 fact, together with others (which I shall give in detail else- 

 where), has led me to suppose that Euchloe arose from an 

 ancient Pieris-stock, which is now most nearly represented by 

 P. protodice and its allies, and that the separation took place 

 on the American Continent. 



" Can insects distinguish between red and yellow .'' — Some 

 weeks ago I wrote a note, which has been read before this 

 Society, on the habits of a certain yellow Thomisid spider, 

 common in this locality, remarking that it seated itself on 

 yellow flowers, and so concealed, captured the insects that 

 alighted on them. Since then I have also found examples of 

 this same yellow spider seated on the flowers of Geranium 

 fremontii, which are of a pale pink colour, and this suggests 

 an inquiry, can spiders and insects distinguish between red 

 and yellow? It is conceivable that the ancestors of Geraniicm 

 were yellow, and that the habit of sitting upon these flowers 

 was acquired at the time by the ancestors of this yellow 

 spider — for although I do not remember to have seen or heard 

 of any yellow flowered Geranium, it is worthy of note that 

 Oxalis, in the same natural order, has both pink and yellow 

 flowered species. But allowing this possibility, it still remains 

 to be asked, does this yellow spider seat himself upon a pink 

 flower because he cannot tell it from a yellow one? and 

 further, can the insects which visit these flowers distinguish 

 between the yellow of the spider and the pink of the flower, 

 and so perceive and elude their enemy? Some time back 

 I noted in the Entomologist that the yellow Gonepteryx 

 rhamni was especially fond of settling upon pink flowers, but 

 it rather appeared that the insect was aware of the conspicuous 

 contrast between these colours. I venture to think this inquiry 



