140 Mr. Poulton's notes in 1885 uj^on 



in the ontogeny of the larvae of this genus to support 

 the view that they have been brightly and very differently 

 coloured in the past (see my previous paper in the 

 Trans. Ent. Soc. Lond., Part II., August, 1885, p. 281, 

 &e.). Such indications are found in the brightly- 

 coloured tubercles on the top of the head ; the occasional 

 suffusion of the light stripes with a reddish tint, and the 

 extraordinary bristles with which the young larvae are 

 covered. At the same time the special explanation of 

 the spots offered above is entirely tentative, for the 

 subject is exceedingly difficult, and many more observa- 

 tions will be necessary before any theory can be 

 considered satisfactory. I have been induced to some- 

 what modify the view I previously brought before this 

 Society, because of the observation of the two larvae of 

 S. ocellatus and the two of S. tilice described above. 



In previous papers read before this Society I have de- 

 scribed the small " eighth stripe " upon the first abdo- 

 minal segment of Smerinthus larvae and in that of Sphinx 

 ligustri. While I was undertaking some extensive 

 breeding experiments upon the larvae of S. ocellatus 

 during the summer of 1885, my friend Mr. W. White 

 (who was staying with me at the time) pointed out that 

 my white larvae possessed a trace of a " ninth stripe " 

 on the last thoracic segment. It is parallel with the 

 " eighth stripe," but smaller than the latter, and very 

 obscure. The best way to see it is to take a general 

 view of the larvae at a little distance. The marking 

 generally disappeared in the last stage, and was, I think, 

 seen in both the previous stages. In a peculiarly white 

 larva found by me in September, 1885, upon Salix alba at 

 Brigue, in Switzerland, the "ninth stripe" was plainly 

 present, although the larva was advanced in the last stage. 

 It seems likely that this obscure marking is due to the 

 tendency towards the transference of serially homologous 

 markings on to those segments upon which they are not 

 present, but, if so, it is improbable that the marking 

 will become distinct, for it w'ould then interfere with the 

 effect of the anterior remnant of the subdorsal in the 

 protective attitude, which the " eighth stripe," on the 

 other hand, rather assists (see Trans. Ent. Soc. Lond., 

 Part I., April, 1884, pp. 32 and 33). The view that this 

 "ninth strijjc" is comparatively recent is also supported 

 by the fact that it is only seen on the whitish varieties, for 



