﻿160 HISTORY AND TRANSFORMATIONS 



The antennae are about three fourths of an inch long, curving over the posterior angles 

 and beneath the head, and the articulations are much contracted. Labium (fig. 6, 

 representing the head beneath) fleshy and bifid, each side obtusely rounded ; labial palpi 

 3-articulate, last articulation fusiform and acute. Maxillae with two fleshy lengthened 

 triangular lobes, the inner one smallest, the external one with a small spine at the apex ; 

 maxillary palpi with five short articulations. Most of the external parts are covered with 

 scattered hairs. 



To allow the imago to escape, the integument of the pupa splits transversely behind 

 the antennae, and longitudinally from this line to the metanotum, into which the cleft is 

 continued for a very short distance. 



Habits. — The insect does not remain long in the pupa state, in which it is inactive, 

 although capable of moving the body in a small degree. Near the period of its final 

 change, however, it acquires the power of walking, although in a very feeble manner; 

 and it seems probable that this power is seldom used. 



3. Imago. (PI. I. Fig. 7.) 



The general color is gray ; the head and thorax brownish, these variegated with spots 

 of pale-flavous. The head and prothorax are minutely scabrous, except the portions 

 spotted with flavous, a character which approximates the imago to the larva. The color 

 of the recent insect scarcely differs from that of cabinet specimens. 



Prothoracic spiracle (fig. e) resembling, like the others, a bivalve shell, but it has 

 the addition of a fleshy pad covered with long hairs, placed at its lower point. Eyes 

 hemispherical, three fourths of a line in diameter; size of the facets .01 of a line, or 

 not more than half the size of those in Libellula and Aeshna. The heart makes from 

 36 to 40 pulsations in a minute. The feet are weak and slender, and the tarsi (/) pen- 

 tamerous. 



The most important peculiarity in the structure of the perfect insect is a complete 

 perforation through the head at the anterior base of each antenna, mentioned by me in 

 the Proceedings of the Academy of Natural Sciences of Philadelphia, Vol. II. p. 192. 

 They are present in both sexes, and are sufficiently large at the narrowest part to admit 

 a bristle, and from this point they enlarge upwards and downwards. They are situated 

 at the internal extremity of a transverse impression above, and in the angle of a curved 

 fissure beneath, which separates the post-mentum from the cranium. They are repre- 

 sented by the semicircular lines shown between the eyes, in figure 8. There is no inter- 

 ruption in the solid exterior of the head as it passes through and lines this perforation, so 

 that thus far it has afforded no additional information as to the functions of the antennae. 



