622 



ZOOLOGY 



aet 



cut 



FIG. 526. Section through 

 the integument of an 

 Insect, base, basement 



covered with thin scales ; in many cases it is developed into tactile 

 hairs or setoe, which may be scattered over the body, or may be 



located only on certain of the appendages 

 the antennae, the maxillary and labial palpi, 

 and the tarsi of the legs. In some, glands 

 are present in the integument odoriferous, 

 honey-secreting, or wax-forming glands ; 

 poison glands are present in connection with 

 an abdominal sting in certain Insects ; 

 spinning glands, forming a silky material, are 

 confined to the larvse. 



The head presents no trace of segmenta 



oT m thT e iuticie; ***?. tion > but tne history of its development in- 

 epidermis; set.' seta, dicates that it may be looked upon as 



(After Miall and Denny.) > -. -. ' a 



composed of a prostomium and about rive 



segments, intimately united together. It varies a good deal 

 in shape, but always presents the regions that have already been 

 described in the case of the Cockroach. Of these the epicranium 

 is the most extensive ; 

 the clypeus, situated in 

 front of it, supports the 

 labrum ; the gence are 

 situated laterally, and a 

 median piece, the gula, 

 occupies the middle of the 

 ventral surface. Some- 

 times the head is sunk 

 within the anterior part 

 of the thorax ; some- 

 times it is free from the 

 latter ; and there may 

 be, as in the Cockroach, a 

 short narrow region or 

 neck, covered with soft 

 skin, supported only by 

 isolated cervical sclerites, 

 on the ventral aspect. 



The three segments of 

 the thorax pro-, meso-, 

 and metathorax are usu- 

 ally firmly united to- 

 gether ; but in some 

 Insects the prothorax is 



LI 4.1 41 FIG 527. A, mouth- parts of the Honey-bee (Apis 



movable upon the Other memfica) ; B, the two pairs of maxilla-. ". eye: 



spo-rnpnt^ it is nsnallv a. antenna ; c. cardo ; ep. epipharynx ; Ibr. labrum ; 



' Udu y li. ligula ; m. mention ; mm, mxi, first pair of maxilke : 



the Smallest of the three md. mandible; pi. labial palpi; pm. palp of the nr-t 



T i ,-, pair of maxillne ; prg. paraglossa ; sin. submentiiin ; 



Segments. In each the ^ m . stipes of the first maxillae. (From Lang.) 



