NEUES P. IMER TT 
of Rhipiphorus paradoxus. 323 
I do not know the time required by Rhipiphorus to go 
through these changes; it is something more than that re- 
cst. by the wasp from spinning-up to emergence ; but what 
is is, I do not know. "That this is much less in the nest 
naturally than in the captive comb is almost certain, as the 
temperature of the nest is, no doubt, very high. In captivity 
it is twelve or fourteen days. Even this period is quite com- 
patible with a larva of Rhtpiphorus of about 5 millims. grow- 
ing in two days large enough to fill up the top of the cell, as 
we see it does before it is full-grown; and this was doubtless 
what Mr. Stone saw, as the Rhdpiphorus-larva becomes a 
pupa at about the middle of the period of twelve or fourteen 
days mentioned above. 
n connexion with this very rapid development of Rhipi- 
phorus, the following fact is very interesting. Many larve, 
when about to assume the pupa-state, present obvious indica- 
tions of the eyes of the imago beneath the skin of the second 
or even of the third segment. This, we have just seen, occurs 
m Vespa; and on this, with some other facts, Ratzeburg 
founded the remarkable, though untenable, theory that the 
head of the imago was the first and second segments of the 
larva combined. In reality, the rapidly developing head 
leaves its previously too small quarters, and finds room by 
pressing backwards the other parts beneath the effete skin; 
and having done so, the various parts of the head, and first of 
all the eyes, begin to show themselves as development pro- 
ceeds. In most insects this is a aap involving several 
le; nor is any change observable until after the larva has 
done feeding. “Having examined a full-fed larva of Rhipi- 
The young external larva is semitransparent, with none of 
the masses of white fat that obscure the interior of the full- 
grown larva, and render it white and opaque. Each of the 
first five segments after the head presents two large dorsal p 
minences, one on each side; and the tracheal system and in- 
testine can be easily made out. The latter is riri simple 
