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EDW. JACOBSON, PLANIPENNIA FROM JAVA. 
Myrmeleonidae are capable of sustaining prolonged fasts, appa- 
rently without any harm. 
The Javanese name of the larvae is: »oundour-oundour«, 
derived from moundour, which means to go backwards, after 
their well known mode of locomotion. 
The cocoon is spherical, and has a diameter of about 
7!/, mm. It is made in the dry and loose soil, and spun of 
white silk. The opening, from which the imago emerges, is 
not cut oat by the pupa, as has been, hitherto, generally 
supposed, but I found, that, in making the cocoon, the larva 
already provides for a trapdoor, consisting of a semi-circular 
flap, on one side (the hinge) continuous with the cocoon itself, 
and on the three other sides fastened with a few threads only. 
This trapdoor is easily pushed open by the pupa when emer- 
ging from the cocoon. 
The pre-existance of the trapdoor can be easily prooved, 
by pulling at a newly finished cocoon in different places with 
a pair of tweezers. The trapdoor will then soon be found to 
yield to a gentle pull, whereas the other parts of the cocoon 
offer a greater resistance, before a fragment can be torn from 
them. This arrangement is not only found with Myrmeleon 
frontalis, but all the other species of Myrmeleonidae, I observed 
in Java, showed the same structure of the cocoons. It is 
therefore very probable to me, that it is a general habit ot 
the Myrmeleonidae (and also of another family of the Plan- 
pennia, as will be seen further on) that it is not the pupa 
or imago, which, with its mandibles, cuts a hole in the cocoon, 
as an exit for the imago, but that the larva, in spinning the 
cocoon, already provides for a trapdoor. 
The pupa, of which Dr. van der Weele has given a figure 
in bis paper, is, when hatched, yellowish with brown spots; 
it is curved, and has a length of only 6 mm. When it has 
reached maturity, it acquires the darker colour of the imago, 
stretches itself, and pushes open the trapdoor. Then only the 
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