NEUROPTERA. 445 



always transports its domicil along with it, protrudes the anterior extremity 

 of its body while progressing, never quits its dwelling, and when found to 

 do so, retiu-ns to it voluntarily when left within its reach. 



When about to become nymphs, they fix their tubes to different bodies, 

 but always in water, and close the two orifices with a grating, the form 

 of which, as well as that of the tube itself, varies according to the species. 

 In fixing their portable dwelling, they so manage it that the aperture, 

 which is at the point d'appui, is never obstructed. 



The nymph is furnished anteriorly with two hooks, which cross each 

 otiier and somewhat resemble a rosti-um or snout. Witli it, when the pe- 

 riod of its last metamorphosis has amved, it perforates one of the grated 

 septa in order to procure egress. 



Hitherto immovable, it now walks or swims with agility, by means of its 

 four anterior feet, which are free, and furnished with thick fringes of haii-s. 

 The nymphs of the large species leave the water altogether, and climb on 

 various bodies, where their final change is effected. The small ones 

 simply rise to the surface, where they are transformed to winged Insects, in 

 the manner of the Culices and various Tipularix; their exuvium serves them 

 for a boat. 



There are several subgenera. 



ORDER IX. 



HYMENOPTERA(l). 



In this family we still find four membranous and naked wings, and 

 a mouth composed of mandibles, maxillae and two lips; but these 

 wings, of which the superior are always largest, have fewer ner- 

 vures than those of the Neuroptera, and are not veined; the abdo- 

 men of the females is terminated by an ovipositor or sting. 



Besides their compound eyes they are all provided with three 

 ocelli. Their antennae vary, not only according to the genus, but 

 even in the sexes of the same species; generally, however, they are 

 filiform or setaceous. The maxillae and labium are usually narrow, 

 elongated, and fixed in a deep cavity of the head by long muscles, 

 form a semitube inferiorly, are frequently folded up at their extre- 

 mity, and better adapted for the transmission of nutritious fluids than 

 for mastication; in several they form a proboscis. The ligula is 



(1) Membrane-winged. 



