12 ON SOME INSECT DEFORMITIES. 
The chrysalis was of medium size, rather lively, and perfectly devel- 
oped. To the upper part was fastened with a collar the caterpillar’s 
head, split in two lateral parts, which are united together in the com- 
mon caterpillar head. The mouth parts of the caterpillar were still 
remaining, but between them another prolongation could be seen. The 
nympha is figured in different views, Figs. 1-4. 
The chrysalis transformed, August 26, into a moth with the caterpil- 
lar head. The chrysalis had the skin split as usual on the dorsal part. 
So the moth left the chrysalis in the usual way, and was perfectly 
developed (Fig. 5), except that the right foreleg was smaller than the 
left one, but otherwise well formed. ‘Therefore the moth stood some- 
what obliquely. It was a male, rather lively in his movements, and 
used both forelegs to push off the caterpillar head, by which it was 
seemingly annoyed. The head of the caterpillar covered exactly the 
place where the head of the moth should be, so that nothing was to be 
seen of it, nor of its antenne or eyes. On the prothoracic border the 
same elongated part was to be seen as in the chrysalis, without any 
hairs, consisting only of a brownish membrane ‘The side parts of the 
head were fastened to it just as in the chrysalis. The right part was 
taken off, and beneath it the right antenna was discovered, well formed, 
but coiled up. In taking off more of the skin, a well-formed eye of the 
perfect insect appeared. 
Mr. Bruinsma explains the fact by the difference of the last moult 
from the four preceding ones. He states that in the last moult the 
skin splits near the tail, and the chrysalis comes out backwards, by 
which process the head is sometimes not able to follow. I confess that 
this statement is entirely new to me, and disagrees with Malphigi’s 
description. 
Mr. Bruinsma concludes his paper with some observations made on 
caterpillars which, after having spun the cocoon, were taken out and 
obliged to spin a second cocoon. This was only imperfect, so that a 
full observation of the caterpillar was possible. Mr. Bruinsma observed 
that one of them formed a chrysalis with the head of the caterpillar. 
But the chrysalis died very soon. Two of the caterpillars are figured. 
Professor J. Van der Hoeven has published a paper in the same jour- 
nal, following that by Mr. Bruinsma, pp. 271-275, about perfect Lepi- 
doptera with the larval head remaining. He draws attention to an old 
observation by J. Jonston, published in his Hist. Natur. de Insectis, 
Amstelod, 1657, p. 123 (Edit. Heilbr., 1768, p. 176). The account by 
J. Jonston is very detailed, and concerns a male and a female of B. 
Mori. The male was in the chrysalis state, the anterior part covered 
with the parts of the caterpillar. The imago was not able to cast off 
the skin, died, and was dissected. The head of the imago was found to 
be fully developed. 
