AMORPHINjE. 389 



of very definite little horns, side by side, in which the two halves of the epicranium 

 terminate above and in front. In 31. tiliae these also exist, but are not very obvious 

 unless looked for. In A. populi they are absent unless two points, not close together, 

 and just like the other minute tubercles of the head, though a little larger, represent 

 them. The comparative form of the larvae of 31. tiliae and S. ocellata may be shown 

 by the measurements of specimens fullgrown in second stage : S. ocellata — length, 

 14mm., thickness, 2'5mm. 31. tiliae — length, 18mm., thickness, 2*imm. Third 

 instar. — The larva of A. populi in third instar has the hairs crowning the now very 

 numerous tubercular or mammillary spots extremely minute, and apparently with 

 no terminal branchings or dilatations. The bases of the bristles on thoracic legs are 

 raised into mammillae, but not to the degree found in S. ocellata. The larva of S. ocellata 

 in third instar has the very numerous tubercular dots or mammillae white, and these 

 mark out the stripes by their larger size along their lines of direction. They carry 

 very small pale hairs, and these are still very distinctly bifid at their extremities, as 

 also those on horn, which is bifid at extremity, but without hairs ; these mammillae 

 also invade the surface of the thoracic legs, which are usually so smooth (apart from 

 ordinary -bristles), as well as the very pronounced double red frontal horn, which is 

 a specialisation of the tubercles. The larva of 31. tiliae in the third instar has minute 

 hairs on mammillary points apparently simple as well as those upon caudal horn ; 

 true legs slightly tubercular. It reserves its long slender facies (Chapman). 



Larval head. — The head of the larva of A. populi in 1st stadium appears to 

 be triangular in comparison with those of S. ocellata and M. tiliae. It is not actually 

 triangular, but has a decided tendency to lengthen and to become pointed at apex when 

 viewed from the front. It is worthy of note that it is less angular in adult stage than 

 are those oi 31. tiliae and 6*. ocellata (Bacot). 



Pupa. — The pupae of 31. tiliae and S. ocellata are enclosed in a frail cell or 

 cocoon, composed of earth, spun together with a few slight silk threads. In the 

 case of A. populi, I could find no trace of silk, nor were the pupae enclosed in 

 a cell, although they were supplied with the same material as the others in 

 which to pupate. As a rule, those of A. populi are only just beneath the surface, 

 while the larvae of M. tiliae and S. ocellata may burrow to a depth of several inches. 

 The difference between the pupae of the Amorphids and those of the rest of the 

 Sphingidae is very striking ; the chief points are the shortness of the wing-cases 

 and the complete absence of the sheath of the tongue, in addition to which, they 

 are thicker and more rounded, the head is small and does not project so far, and 

 the small size of the eye-cases is very noticeable. On the surface, the pupae of 

 31. tiliae and A. populi are much alike, the latter being rather the rougher of the 

 two. The bosses on either side of the anus are very distinct in both species. In 

 colour, the pupa of 31. tiliae is of a deep red-brown, while that of A. populi is 

 of a dead black with, when quite dry, a slight greyish tint on the antenna -cases 

 and other raised surfaces. In shape, that of 31. tiliae is more like that of S. 

 ligustri than that of A. populi, which is by far the shortest and dumpiest of the 

 three. The pupa of S. ocellata comes between the other two as regards shape, 

 but is much more rounded at the anal end, the bosses on either side of auus being, 

 as a rule, hardly visible ; it has a smooth polished surface, and is of a deep brown 

 or black colour. The anal spike is largest and thickest in 31. tiliae, in S. ocellata 

 it is smooth and relatively smaller, while in A. populi it is much smaller, and 

 generally sharp and slender (Bacot). 



Lmaginal frenulum. — The imago of 31. tiliae possesses the loop and 

 bristle fairly well developed, and certainly quite effective, as the 3 has a well- 

 defined loop, and the bristles of the ? are sufficiently long to interlock with the 

 scales of the forewing. In S. ocellata the male has a very short bristle, and 

 the female a cluster of very small ones ; the loop of the male is absent, 

 and the whole appliance is probably useless, or nearly so. The male of A. 

 populi possesses the prominence on the hindwing from which, in other 

 species, the bristle proceeds; this is rounded in outline, and, in some few examples, 

 terminates in a minute point, which can hardly be called a bristle ; all the female 

 specimens which I have examined microscopically, have a very small but perfectly 

 formed bunch of bristles lying close to the edge of the wing, but clearly in both 

 sexes the appliance is quite useless and is merely a survival. [Although for the 

 sake of simplicity, it may seem well to follow the usual course of uniting our three 

 British Amorphids in one genus, yet, taking into account the allied European and 

 Exotic species theie is probably gcod giound for considering tiliae at least to be 

 generically distinct from the other two, even if they are not all three representatives 

 of different genera, not in respect 01 diversities of the frenulum alone, but in view 

 of many other points] (Griffiths). 



