CELERIO GALLII. 187 



ber 1 2th (Of the appearance in this, the 5th instar, May gives no 

 account). The markings of the larva of this species appear to 

 be developed in a precisely similar manner to those of Thaumas 

 vespertilio (vide, Weismann, Studies in Theory of Descent, pp. 210-21 1). 

 He says that the adult larva, as in that species, shows no trace of a 

 subdorsal line. A row of large black spots, each having an irregular, 

 round, yellowish-white nucleus is situated on an olive - green, 

 blackish-brown, brown, or dirty yellow ground. A figure of a larva 

 by Hiibner is 2*5cm. long, of a light green colour, with five longitud- 

 inal lines — cne dorsal, two subdorsal, and two spiracular lines. The 

 subdorsal is white, and bears, in the place of the ring-spots, small 

 red dots, whilst the line itself is bordered with black where the 

 red spots are situated. Hiibner's figure is possibly of the ^rd stage, 

 so that it is probable that, in the second stage, there is a subdorsal 

 line either quite free from spots, or only showing such feeble rudi- 

 ments* as are to be seen in the 2nd larval stage of T. vespertilio. Of 

 two larvae in the \th stage, found in the Upper Engadine, one (fig. 

 45) was 3' 3cm. long, already of a dark, blackish-green ground- 

 colour, with a broad greenish-white subdorsal line sharply defined 

 throughout its entire length, and containing ring-spots of a sulphur- 

 yellow, with an orange-red nucleus; the black "ground-area" did 

 not encroach upon the subdorsal line, but was confined to two 

 faint crescents situated above and below the "mirror." Only the 

 two foremost " mirrors " (on the 2nd and 3rd segments) were 

 without nuclei. The remaining peculiarities of coloration are 

 shown in the figure. The shagreening is present on the sides 

 and a portion of the under surface. A second example was 2*8cm. 

 long, essentially similar to the former, but was pitchy-black, with 

 a very indistinct subdorsal line and a few ring-spots, the "mirrors" 

 of which were also sulphur-yellow, with an orange-red nucleus. 

 The shagreening was quite as strong as in the first specimen, the 

 dots being yellow instead of white. It is specially to be observed, 

 because of its important theoretical bearing, that, in this larva, the 

 ring-spots were absent on the front three segments, and on the 

 fourth only a faint indication of one could be perceived. In the 

 larva figured, the ring-spots increase also in distinctness from the 

 tail to the head. %th stage : The two specimens just mentioned, 

 after moulting, acquired the well-known markings of the adult larva, 

 already briefly described above. The 5th is the last stage. The 

 larva is known to occur in several varieties, Rosel having figured 

 it in three forms — light green, olive-green and dirty yellow. Having 

 had an opportunity of observing 25 adult specimens at one time, 

 I am able to state that it is not in this instance di- or polymorphism! , 

 but a case presenting a great deal of variability, with which we 

 have to deal. There are not several sharply-defined types of 

 coloration, but the extremes are connected by numerous intermediate 

 forms ; the extreme forms, however, certainly preponderate . . . 

 Among the 25 larvae, all gradations of colour, from pitchy-black 

 to light clay-yellow, occurred, and even to an almost whitish- 



* This is so. See summary (supra p. 1867, where it is stated that the 

 indications of the spots only are to be found in the 2nd instar. 



t Weismann appears here to use the term polymorphism in a restricted sense, 

 and to exclude those cases where many marked types are joined by intermediate 

 forms. 



