﻿OF CORYDALUS CORNUTUS. 159 



which moves freely in the torulus (Z). The mandibles (fig. 2, m) are robust, with the 

 apex strongly 4-dentate. Maxillae (fig. 3, m') composed of a short cardo, and a straight 

 stipes flattened above and convex below, the sides parallel and the inner margin ciliated, 

 the apex rounded, with two articulate projections representing the labial palpi and max- 

 illary lobe. The former is composed of three, and the latter of two articulations. The 

 labium (/') is corneous, transverse, with the margin undulate, and it has small 3-articu- 

 late palpi. Figure 2 represents the superior, and figure 3 the inferior part of the head 

 enlarged, with the form of the various parts as they are exposed by the separation of the 

 sutures, when the external parts are cast off to enter the pupa state. In figure 2 the 

 labrum, clypeus, post-clypeus, mandible, and antennre are apparent; the post-clypeus 

 separated from the epicranium, from which a small piece is detached by a suture poste- 

 riorlv. Figure 3 exhibits the corresponding inferior parts, with the separation of the 

 epicranium. 



Habits. — The larva is predaceous and aquatic, walking upon the bottom, and not 

 very active. Its locomotion is forwards, but when it is disturbed, it draws itself rapidly 

 backwards by means of the caudal hooks, which are attached to the surface, and the 

 bod)" drawn up. When disturbed, it exhibits the propensity of the imago to bite. The 

 head is sometimes cleaned by passing the anterior feet over it. It is found 'in the spring 

 of the year from a short distance to fifty feet or more from the water, where it takes 

 refuge beneath a stone or log, forming an oval cavity in the earth, where it remains some 

 time (probably not less than two weeks) awaiting its change. It will live in confine- 

 ment four or five days without being wet, so that it is probable that the spiracles are 

 used for aerial respiration. 



Sexes. — In the male larva (and also in the pupa) the head and mandibles are a little 

 larger than in the female, although the form is identical ; and it has a small tubercle upon 

 the middle of the prosternum near the insertion of the feet, somewhat resembling that 

 in the orthopterous genus Acrydium. Figure 1 represents a male larva when full 



grown. 



2. Pupa. (PI. I. Fig. 4, 5.) 



The body of the pupa is curved in a semicircle, and it becomes narrower and more 

 nearly cylindrical, the chief difference (when compared with the larva) being apparent in 

 the prothorax and abdomen. The head resembles more nearly that of the adult, except 

 the mandibles, which are toothed in both sexes, and do not differ essentially from those 

 of the larva. An elevated ridge extends backwards from the posterior portion of the 

 eyes (fig. 5). The wings are deflexed, arid, with the feet, rest loosely upon the breast. 



