NEUROPTERA. 



575 



according to the species, and which have been carefully studied by Messrs. Van dcr Linden and 

 Charpentier ; the legs short, and directed forwards. 



The feiiude, in order to deposit her eggs, places berself upon plants close to the edge of the water, 

 into which she repeatedly thrusts the extremity of her body. The larvae and pnpa^ reside in the water 

 until the period of their final transformation, and are somewhat like the perfect insect, except in 

 wanting wings. But the head, upon which we perceive no ocelh, is remarkable for the singular form 

 of the piece which occupies the place of the lower hp. This is a kind of mask, covering the mandi- 

 bles, maxillcc, and nearly all the under side of the head. It is composed, 1st, of a principal triangular 

 piece, which Reaumur calls the menton7iiere, and which articulates by a hinge with a peduncle 

 attached to the head ; 2nd, of two otlier pieces inserted at the lateral and anterior angles of the pre- 

 ceding piece, moveable at the base, transverse, and entire, in the form of broad and denticulated 

 plates, similar, in their mode of closing the mouth, to a pair of shutters, or in the form of small 

 hooks. The insect is able to close or extend this very quickly, seizing its prey by means of the claws 

 at its upper part. The posterior part of the abdomen is sometimes furnished with five unequal-sized 

 conical plates, capable of opening or closing, and forming a kind of pyramidal tail, and sometimes 

 with three elongated villose plates like oars. These insects may be seen every instant opening the 

 rectum in order to take in a supply of air, when they close it again, and shortly afterwards eject the 

 water with force and mingled with bubbles of air, this action appearing to assist them in their motions. 

 [Its more immediate object is, however, in order to obtain a supply of fresh oxygen from the water 

 thus introduced into the rectum.] When arrived at the period for their final change the pupje quit 

 the water, crawl up some adjacent stem, where they fix themselves by their claws, and scale off then* 

 pupa-skin. 



M. Poey, who has particularly studied the insects of Cuba, has informed me, that at a certain season 

 of the year the northerly winds bring to the city of Havannah and its neighbourhood an innumerable 

 quantity of specimens of one of the spe- 

 cies of Libellula;. [Other instances of 

 their periodical flight or migrations in Eu- 

 rope have been observed. See Dr. ^Yeis- 

 senborn's memoir on this subject in the 

 new series of the Mag. of Nat. Hist.'] 



Fabricius, preceded in this respect by Rt^au- 

 mur, divided the Drag:on-flies into three g-enera. 



LibelUda proper, has the wings extended 

 horizontally in repose; the head nearly gloliu- 

 lar, with the eyes very large ; a vesicular eleva- 

 tion, having- on each side an ocellus, upon the 

 vertex ; the other ocellus, or the anterior one, 

 is much larger, and the middle division of the 

 lower lip nmch smaUer, than the lateral ones, 

 which, closing by a straight suture, exactly 

 shut the mouth. The abdomen is generally 

 broad and flat. The larvai and pups have five 

 appendages at the extremity of the body, which 

 is short. Type, L. depressa, Linn., [a very 

 common llritish species, a.s well is L. cancel- 

 Jala, liere ligured, the males in both of which 

 are remarkuUle for the fine leadcn-blue colour 

 of their abdomen]. The memoir of Van der Linden on the Libelluls of Bologna, and subsequently upon those 

 of Europe, as well as the Hor<e Entomologicce of M. Charpentier, and a scries of memoirs by M. Boyer de Fonsco- 

 lombe in the Annates de la Society Entomologique de France, may be consulted. The British species, distributed 

 into various genera, have been described by Mr. Stephens.] 



yEshna, Fabr., is similar to Libehula in the manner in which the wings are carried when at rest, and in the form 

 of the head, but in whicii the two posterior ocelli are situated upon a simple transverse elevation, having, more- 

 jver, the middle lobe of the lower lip larger, and the two otiiers wide apart, and armed with a strong tooth or 

 spine ; thp abdomen is always long, narrow, and cylindric. The body of the larvffi and pLip;e is also moi'e elongate 

 thaii in those of Libellula ; the mask is Ilat, witli its two hooks narroiv, and armed with a moveable hook at the 

 tip. Libellula grandis, [a common Fnglisli species, two iucht-s and a half long, and many others]. They fly with 

 t^tunishing rapidity over the maririn of waters, pursuing flies and other insects in the same manner as swallows. 



