100 



MODERN CLASSIFICATION OF INSECTS. 



large, oval, or rounded, and depressed, united to the following segment 

 by a short neck, with five or six small elevated tubercles near the an- 

 terior angles, representing the eyes. They have two rudimental slender 

 antennae, about as long as the head, inserted in front of the eyes, and 

 composed of seven joints, the first, third, fifth, and seventh of which 

 appear to be merely nodules of the joints which they connect. The 

 mouth is remarkably constructed, being destitute of the ordinary aper- 

 ture, so that the insect may be, and indeed has been, described as 

 wanting a mouth. 



7/ o-:^::^ -^^ \\,\ \^ \\\v 3 \^\ \ n ..^^4in- 



The mandibles i^fig. 6. l.) are very long, hollow, sickle-shaped, and 

 acute, having a longitudinal slit near the extremity, so as to enable 

 the larvaj to suck their prey, the juices running down the mandibles into 

 the head. I have, however, discovered that this canal, which runs 

 within the mandibles and maybe easily distinguished, being apparently 

 covered with a thin membrane only, externally terminates in a small 

 circular aperture at the base, on the upper and internal edge of the 

 jaws.* The maxillse i^jig. 6. 2.), which have hitherto been regarded 

 as part of the external palpi, are slender, cylindric, and terminated by 

 a short lateral spine ; the maxillary palpi being of equal thickness, 

 arising from the tip of the maxilloe, and 7-jointed ; the lower tip(^^. 6. 

 3.) is short and bilobed ; and the labial palpi are slender and 4-jointed, 

 the first and third joints being very short. These palpi, and the organs 

 from which they arise, must here necessarily, from the closing of the 

 mouth, be employed only as feelers. The muscles with which the man- 

 dibles are moved are of a very large size, occupying almost the entire 

 of the interior of the head ; when unemployed, these jaws are closed 

 upon each other in front of the head, which then appears nearly 



* De Geer, after describing the suctorial structure of the mandibles, has sug- 

 gested that the insect must be provided with some other means of taking food, as he 

 observed one of the larvaj not only suck the juices of an aquatic Woodlouse, but 

 also devour, by small degrees, all its solid parts. 



