1872.] 245 [Hagen. 
United States, are known to be pit-fall makers, and to move back- 
wards. In Patagonia and in the Galopagos Islands pitfalls have 
been observed, but the larva is not known. The others go forwards, 
_ or both forwards and backwards, but never construct pit-falls. 
The eggs of the Myrmeleonina are unknown, those of the Ascala- 
phina are fastened in two series on the stems of plants, but in Ulula, 
are placed in circles on the extremity of a twig, which the female 
encircles nearer the base with a kind of fence, to protect the brood 
from intruders. The bodies forming this fence are secreted by the 
female, and are, I believe, similar to the pedicels on which the eggs 
are borne in Chrysopa, the difference being that in Ulula the eggs are 
placed at some distance from the pedicels, instead of on them. This 
remarkable fact, observed by Landsdown Guilding, should be studied 
again. I was able to observe that Ascalaphus in hatching changes 
the skin, just as Osmylus and Chrysopa. This phenomenon occurs 
in none of the so-called Pseudoneuroptera, and forms a striking dif- 
ference between the embryo of the Hemerobina and Odonata. So far 
known, all the species spin cocoons for transformation, and: do not 
previously break off the mandibles, as Osmylus. 
It would perhaps be too soon to give a general view and a synopsis 
of the larve of all the Hemerobina. ‘There are known, besides the 
seventeen genera belonging to the Myremelonina and Ascalaphina, 
the larve of only ten genera, mostly the result of the admirable 
energy of Dr. F. Brauer of Vienna, viz., Mantispa, Coniopteryx, 
Osmylus, Sisyra, Drepanopteryx, Hemerobius, Micromerus, Chrys- 
opa, Hypochrysa and Nemoptera. The twenty-seven genera now 
known in the larval state represent not half of the genera actually 
published, and as many of the most aberrant forms belong to the un- 
known, viz., Nymphes, Stilbopteryx, Polystoechotes, and others, it 
is to be presumed that a synopsis actually drawn up would be very 
soon imperfect by new discoveries. Nevertheless, the larve now 
known agree in several important characters, perhaps not un- 
worthy to be noticed here. All known larve of Hemerobina possess 
the mouth parts fitted for sucking. In connection with this arrange- 
‘ment the posterior part of the alimentary tract does not serve for the 
ejection of digested materials; it is closed and transformed into a 
spinning organ. The structure of the mandibles and maxille, the 
latter playing in a deep groove of the former, is well known, but it is 
overlooked that both have a series of very fine teeth, opposed to each 
other, serviceable for a kind of mastication in the interior of the cap- 
tured animals. The two channels of the mandibles lead directly to the 
