NEUROPTERA. 59 
of their ultimate metamorphosis, ’and, with the exception of wings, 
are tolerably similar to the perfect Insect: Their’ head, however, 
on which the simple eyes are not perceptible, is remarkable for the 
singular form of the piece which replaces the lower lip. . It is akind 
of mask that covers the mandibles, maxillx, and almost the whole 
under part of the head, It is composed, 1, of a principal triangular 
piece that is sometimes arched and sometimes flat, called by Reau- 
mur the menfonniere (chin-cloth), articulated by a hinge with a pe- 
‘dicle or sort of handle annexed to the heads 2, of two other pieces 
inserted at the superior and lateral angles of the former, movable at 
base, transversal, and either in,the’ form of wide and dentated lamine 
resembling shutters in their, motion and the manner in which they 
close the mouth, or in the form of hooks or little claws. To this 
part of the mask where the menfonniére is articulated with its pe- 
dicle, or the knee, and which appears to terminate it inferiorly when 
the mask is flexed upon itself, Reaumur applies the name of mentum. 
The insect unfolds or extends it with great promptitude, and seizes 
its prey with the pincers of its superior portion, The posterior 
extremity of the abdomen sometimes presents five foliaceous and 
unequal appendages, which the .animal can separate and approxi- 
mate, in which case they form a sort of pyramidal tail; sometimes 
we observe the three elongated and.pilose laminz or a sort of fins. 
We see thése Insects unfold them every moment, open their rectum, 
fill it with water, then close it, and shortly afterwards ejaculate that 
water mixed with large bubbles of air,a game that appears to facili- 
tate their motions. The interior of the rectum(1) presents to the 
naked eye twelve longitudinal ranges of little black ‘spots, approxi- 
mated by pairs, resembling’ the pinnated leaves of botanists. By 
the aid of the microscope wer discern that each of these spots is 
composed of little conical’ tubes, organized like trachez, and from 
which originate small branches that proceed to six large trunks of 
the principal trachez that traverse the whole length of the body. 
Having attained the period of their ultimate metamorphosis, the 
nymphs issue from the water, climb along the stems of plants, fix 
there, and divest themselves of their skin. © 
M. Poe, who has paid particular attention to the Insects of the 
island of Cuba, informs me that at a certain season of the year the 
northern winds. sweep an-innumerable host of a species of this genus 
~~specimens of which he had the kindness to send me—into Havana 
or its environs. 
(1) Cuy., Mém. de la Soc. d’Hist. Nat., 4to, p. 48. 
