lepidopteroiis larvcB and pupce. 139 



with the faintest tinge of red in its centre. There was 

 also the shghtest trace of red round the spiracles, 

 spreading outwards from the normal red line. Omitting 

 the last feature the description is exactly the same as 

 that quoted from Weismann, referring, of course, to the 

 larvfe with the " mere trace " of the spots. The other 

 larva of S. oceUatiis had the spots rather more developed, 

 and the}^ first appeared in the fourth stage. They were 

 only i^resent in the upper row on the second thoracic 

 segment {very faint) and upon the first five and the 

 seventh abdominal segments. This larva died when it 

 was advanced in the last stage, the spots being the same 

 as in the previous stage, but the chief interest of the 

 larva lay in the fact that it was 7iot a yellowish variety, 

 but intermediate between this and the whitish form. In 

 all the other instances hitherto recorded the spotted 

 varieties of ;S'. ocellatus have always belonged to the 

 yellowish form of the larva (as did the other larva of 

 this species mentioned above). These two larvfe have 

 been described in a paper read before the Eoyal Society, 

 and to be published in the Proc. Roy. Soc. in a few 

 weeks. It must be remembered that the purple borders 

 of >S'. ligvstri are linear, and not spot-like in their first 

 appearance, and that the spots of S. tilicB only appear 

 in one row (as far as I am aware) instead of two or three 

 rows, as in the other Smerinthus larvae. It seems 

 possible (but this is a mere suggestion) that the coloured 

 borders existed in Smerinthns larvae, arising in the same 

 manner as in Sphinx ligustri by a linear substitution of 

 a bright colour for the previous border of darkened 

 ground colour, and that the appearances seen in 

 Smerinthus tilia are due to the fading away of the 

 character instead of its origin. The borders are fairly 

 complete in some individuals, in others they shorten 

 into spots, but in the large majority they have dis- 

 appeared. In the other Smerinthus larvae the shortening 

 borders may have been arrested at the spot stage, which 

 has evidently been made use of as an independent larval 

 marking, and which has received additions in the other 

 rows. The great length of time over which the spots 

 have been made use of as a larval marking (in S. ocellatus 

 and S. popidi) may account for the fact that the sj^ots 

 only, and never the coloured borders, appear in the 

 ontogeny of these two Smerinthus larvae. There is much 



