NOTES ON HYBRID SMEKINTHU8 POPULI-OCELLATUS. 301 



(yellow) ; they are, however, situated, as in S. ocellattis, close together, 

 and not a short distance apart with two smaller ones between, as is the 

 case in the larva of -S. populi. Body : becomes j)aler towards close 

 of this stage, though not so white as *S'. ocellatm. Stripes : oblique 

 stripes, as in S. tiliae and N. ocellatm, 1 to 5 equal, 6 narrow and 

 weak, 7 strong and broad. The sub-dorsal line is faint and narrow, 

 is continued backwards to the 7th oblique, but barely noticeable on 

 thoracic segments ; a double medio-dorsal stripe is faintly marked ; 

 the anus outlined with same colour as other stripes. Caudal horn : 

 long and very thick at base. Hairs : still bifid, but this character is 

 not quite so marked in the hybrid as in the larva of <S'. ocellatus. Habits: 

 the larvjB rest either with the head downwards («S'. populi habit) 

 or with it upright {S. ocellatus position), with the first two pairs of fore- 

 legs withdrawn, though not so completely as is the case in ;S'. ocellatm. 



One larva is growing to a large size in this stage, it is already 

 over one inch long, and shows no sign of an approaching moult. 

 The larva of S. ocellatus, when about to moult in this stage, is of 

 about the same length as this larva now is, but it is not nearly 

 so bulky. By July 12th there were only 19 living larvae ; three were 

 well grown in the 4th skin, the remainder mostly in 3rd. They 

 varied in colour from a yellow-green to a pale whitish sage-green, and 

 were tolerably constant in shape, but very variable in size. 



ith skin : July 12th. Head : as previously described. Body : the 

 7th oblique stripe is faintly continued forwards to the 3rd pair of pro- 

 legs ; the 1st oblique runs forward to the pro -thorax. The small 

 oblique stripes that are present in S. populi, just above base of pro- 

 legs 1, 2 and 3, can be faintly traced in the hybrid larva. The larvae 

 now mostly rest in the position taken by that of S. populi. Both 

 yellowish and whitish forms are present in this stage. Just after the 

 3rd moult the yellow forms are superficially very like N'. populi in 

 its 3rd skin, the only striking dift'erence being the absence of any 

 strengthening of the 1st oblique stripes. July nth. One is now 

 nearly full grown, in 4th skin, while the majority of the remainder 

 are about to undergo a 4th moult. 



Full-fed larvae in 4th skin, July 17th. — Head : not so large or 

 tall as that of S. ocellatus in 5th skin, and the yellow bands down the 

 sides of the face are stronger and broader. The resemblance of the 

 tubercles, and their position on apex, is remarkably close to S. 

 ocellatus in everything except colour. This is, however, partly due 

 to the fact that with iS. ocellatus in the adult stage (5th skin) the 

 tubercles or processes have greatly dwindled in size. Body : in colour 

 it now almost exactly resembles a typical larva of .S'. ocellatus. The ob- 

 lique stripes are now much stronger than when it first changed into this 

 skin ; the sub-dorsal is very weak and faint ; the spiracles, bright red ; 

 in N. ocellatus they are deep crimson, and much larger. Anal flap 

 outlined with yellow, in -S'. ocellatus with white. In general shape and 

 habits it is still very similar to S. pojndi, and is restless under 

 examination, as in this species. The larva of S. ocellattis, on the other 

 hand, will usually retain its stiff and rigid resting position during the 

 process, unless greatly provoked. 



The first larva went down on July 21st, having only undergone 

 three moults. By the 24th, the majority were full-fed, or nearly so, 

 and the remainder, with one or two exceptions, were in the final stage. 



