PERFECT INSECTS WITH THE LARVAL HEAD. 
9 
tion of other parts ; even if the untransformed parts are important to 
the life of the animal. He believes this to be a natural consequence of 
the segmentation of the body of the arthropods. 
2. The accidentally covered parts nevertheless go through all trans- 
formations which are necessary for the insect to arrive at the imago 
state. The second conclusion is of course not to be accepted, if the 
facts recorded by Mueller are adopted. 
Morpho Eurylochus. 
Among about a dozen specimens of this butterfly brought home by 
Professor L. Aimssiz from Brazil, one male has retained the head of the 
caterpillar. The specimens are from Canta Gallo, communicated by 
Dr. Teuscher. Their perfect condition leads me to suppose they were 
reared from the chrysalis. 
The quoted male is in perfect condition, and, as all others, entirely 
well developed in size and in colors. The head of the caterpillar is 
retained and perfectly preserved in shape and in color; the minute 
yellow hairs which cover the head are in good condition, and the 
spines are scarcely crumbled. Beneath the head the mentum is 
broken off near the prothorax. Its lateral sutures are separated, and 
the mentum hangs down as a kind of trap-door, being united with the 
head only by a small anterior lobe. This kind of adjustment leads me 
to suppose that the mentum was broken by the pushing out of the 
spiral tongue of the imago. The opening is large enough to show that 
the head of the caterpillar is empty inside. The skin between the 
head and the prothorax is still preserved in the shape of a contracted 
ring, which is open only for a small space beneath, where the mentum 
is separated. The large dorsal plate of the prothorax is present, and 
covers loosely the thorax of the imago ; on the left side the external 
third is wanting. The palpi are rejected to the thorax, but the right 
palpus has the two basal thirds covered by the skin of the caterpillar, 
which is connected with the dorsal part of the prothorax. Behind the 
palpus and rather near to it can be seen the free foreleg of the right 
side. Its limbs are well developed, neither as stout nor as hairy as in 
the other specimens. The left palpus, though not covered, seems to be 
shorter and less hairy than the right one. The left foreleg is covered 
by the femur of the middle leg. I am not able to state whether any 
part of the skin of the chrysalis, either beneath the dorsal plate of the 
prothorax on the middle and on the right, or on the entirely free left 
side of the thorax, is present. Perhaps the skin of the chrysalis is 
broken oft' just at the ring formed between the head and the prothorax. 
I am unable to see the skin of the chrysalis inside of the head of the 
