I N S 



O*l/t 



.tend lobes its form is more or less rounded, but it 

 of C ; a triangular or heart-shape ; occas.on- 

 allv, as in the caterpillars of some butterfly, the two 

 lobes are terminated by spines or tubercles. . Ihcre 

 are other variations in the appendage. , by jAtch this 

 part of the body is distinguished. In the second sec 



ion above described, the head is generally ret actile, 

 membranous, and variable in form, and destitute of 

 oyeT and antenna,, as well as of the ordinary par s of 

 the mouth, which appears only to . consist of pair oj 

 hooks, or bristles, which are incapable ot either cutting 

 or grinding; the insect employs them not on ,1 j 'to pierce 

 the soft matters, upon the juice ol which it feeds, but 

 also as claws whilst engaged in locomotion. 



ECT. 



structure of various organs of the mouth, which it may 

 be interesting to notice. Thus the jaws of the ant- 

 lion fly, and of the predaceous water beetles, are very 

 long, slender, curved, and sickle-shaped, having a 

 small longitudinal aperture near the extremity, which 

 communicates with an internal canal, through which 

 the juices of the prey of the insect pass. Another 

 remarkable peculiarity exists in the elongated elbowed 

 structure of the lower lip of the larvae of the lihdlit- 

 lldce (dragon-flies), which we have already described, 

 and which is employed like an arm furnished with 

 claws for seizing their prey. Again, in those larvie 

 which spin for themselves silken cocoons, in which 

 they undergo their transformations, the lower lip is 

 furnished at its extremity with a minute and slender 

 organ (fig. 21, ') which Kirby and Spence have aptly 

 termed the spinneret (fusulus), composed of several 

 longitudinal slips alternately corneous and membra- 

 nous, whereby the insect has the means of contracting 

 the tube, which terminates in a single orifice, and 

 through which the insect emits its silken threads, which, 

 although elaborated in two distinct silk tubes, unite 

 previous to their emission from the orifice of the tube. 

 Some larvae, indeed, spin a silken thread for the for- 

 mation of cocoons from a distinct apparatus at the ex- 

 tremity of the body. ( 



The liead of larvae is generally provided with a pair 

 of short rudimental antenna^ eve. ard organs of the 

 mouth. 



The antennae (fig. 20, b) ai* placed near the base 

 of the mandibles ; they are for toe most part totally 

 unlike the antennae of the perfect insect, although in 

 the homomorphous section they are very similar in 

 this respect, although shorter, and composed of fewer 

 joints. These organs are, however, in general very 

 short, and composed of three or four joints ; and in 

 many groups they are entirely wanting in the larva 

 state. 



The eyet of larvae are not, like those of the perfect 

 insect, formed of an innumerable series of hexagonal 

 lenses, but consist of a small number of simple gra- 

 nular tubercles, placed at the sides of the head, in 

 the same situation that the eyes of the future insect 

 are to be developed ; they are, therefore, more ana- 

 logous to the simple eyelets of many insects which we 

 shall subsequently describe under the name of ocelli ; 

 many larvae are, however, entirely destitute of them. 

 Their numbers, when present, seldom exceed six on 

 each side, which is the number possessed by the cater- 

 pillars of butterflies (fig. 20, a). The larvae of the 

 dragon flies have eyes somewhat resembling those of 

 theperfect insect. 



The inouth of the majority of larvae consists, like 

 the mouth of the perfect insect, of an upper lip (fig. 

 20, c), a pair of horny jaws (fig. 20, d), a second or 

 lower pair of jaws of less firm consistence (fig. 21, e), 

 furnished with an articulated palpus (fig. 2 1,/), and 

 a lower lip (fig. 21, g), furnished also with a pair of 

 articulated palpi (fig. 21, h A). Here, however, we 

 nave to remark that the structure of the mouth of the 

 larva will, by no means, lead us to a correct idea of 

 the mouth of the imago ; thus the jaws of the cater- 

 pillars of butterflies are as robust, and not very unlike 

 those of the larvae of beetles : but the mouth of the 

 former consists of a slender spiral and tubular appa- 

 ratus for sucking up honey, whilst that of the latter 

 retains much of the general appearance of the mouth 

 of the larva. There are some peculiarities in the 



22 



We now pass to the description of the other 

 segments of the body of larvae, and the organs of mo- 

 tion, and other appendages with which they are 

 provided. Generally speaking, these segments, which 

 are typically twelve in number, are of a cylindrical and 

 elongated form ; but various modifications occur, 

 some larvae being flattened, others oval, some short 

 and thick, others having the segments very irregular, 

 warty, spinose, or hirsute. The three anterior seg- 

 ments are, however, ordinarily distinguished by 

 each having on its inferior surface a pair of short 

 scaly legs, composed of four or five joints, which are 

 analogous to those of which the legs of the perfect in- 

 sect are composed, and generally terminated by a 

 small claw (fig. 22). In many larvae, as we have in- 

 dicated in the table given above, these are the only 

 legs with which the insect is furnished, although it 

 rarely occurs that these are wanting, the organs of 

 motion being the merely rudimental prolegs. These 

 prolegs are thick, and of a membranous construction, 

 so that, unlike the true articulated legs which are ca- 

 pable of motion only at the articulations of the joints 

 these are completely flexible. These legs are exclu- 

 sively adapted to the insect whilst it remains in the 

 larva state, there being nothing at all analogous to 

 them on their arrival at the perfect state. These legs 

 are furnished at the extremity with a multitude of 

 minute bent hooks, which are employed by the larva 

 in retaining its situation, upon whatever substance it 

 may happen to be placed, with very great firmness 

 (fig. 23 and 24). These prolegs are very variable 

 both in their structure and situation, as also in their 

 number varying from two to eighteen. These 



