of certain lepidopterous larvcs and pupce. 33 



(PI. I., fig. 4). The effect is heightened by the slight 

 oblique stripe on the 5th segment, for the eye naturally 

 regards this as the true continuation of the subdorsal. 

 The curving and contraction of the anterior segments 

 do not produce perfect parallelism, but quite enough 

 for the eye to accept the subdorsal as part of the series 

 of oblique stripes. It is an instance of an imperfect 

 suggestion being sufficient to continue a series of mark- 

 ings, and to be efficient in protection. I have no doubt 

 that this is the cause of the retention of the anterior 

 part of the subdorsal and of its gradual disappearance 

 posteriorly. When the larva is at rest the contraction 

 of the anterior segments is so great that the spiracle on 

 the 2nd segment is always partially and sometimes com- 

 pletely hidden. Fig. 4 shows the attitude of rest, but 

 the same larva as that drawn in fig. 3 has been here 

 given, and the subdorsal is in consequence less sub- 

 ordinated to the oblique stripes than is usually the case. 



The same adaptation of an older system of markings 

 to a more recent oblique line system is seen in other 

 larvae, as well as in the Sphingidce. Thus, in the larva 

 of Endromis versicolor, as depicted on page 203 of New- 

 man's ' British Moths,' a distinct dorsal line is drawn, 

 and another line, which appears to be spiracular in the 

 2nd segment and subspiracular in the 6th. There is 

 also the oblique line system consisting of eight stripes 

 (which slope in the opposite direction to those of 

 Sphingidce) upon segments 4 — 11 inclusive. The spi- 

 racular line is distinguished by a longitudinal row of 

 dots, as well as by its position. It appears to be normal 

 in segments 2 — 6, but on the 7th segment it becomes 

 oblique, and forms a continuation of the true oblique 

 stripe on the 6th segment. This is also the case upon 

 all the segments up to and including the 12th. In each 

 case the true oblique line upon one segment is continued 

 posteriorly on to the next segment by a modification in 

 position of the subspiracular line upon the latter. Al- 

 though modified, the subspiracular oblique lines retain 

 their characteristic dots, and it is thus easy to recognise 

 this portion of the stripe as belonging to a different system, 

 which is retained unchanged anteriorly. This is there- 

 fore an extremely interesting adaptation of an older to 

 a newer form of marking, which has taken place where 

 the latter is chiefly developed (after the 6th segment). 



The larva thus represented is certainly adult, and I 



TBANS. ENT. SOC. LOND. 1884. — PAKT I. (APRIL.) D 



