622 



ZOOLOGY 



SECT. 



FIG. 526. Section through 

 the integument of an 

 Insect, base, basement 

 membrane ; cut. layers 

 of the cuticle; epi. 

 epidermis ; set. seta. 

 (After Miall and Denny.) 



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

 hairs or setce, 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 larvae. 



The head presents no trace of segmenta 

 tion, but the history of its development in- 

 dicates that it may be looked upon as 

 composed of a prostomium and about five 

 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 ^ tfL * 

 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^&iQ usu- 

 ally firmly united to- 

 gether ; but in some 

 Insects the prothorax is 



mnvfl'hlp iinon fhp nfliAr FlG - 527. A, mouth-parts of the Honey-bee (Apis 



mellifica) ; , the two pairs of maxillae, au. eye ; 



Segments I it IS USUallv a - an tenna ; c. cardo ; ep. epipharynx ; Ibr. labrum ; 



TT , f ., ., J li. ligula ; m. mentum ; mm, mx it first pair of maxillae ; 



tne Smallest OI the three md. mandible ; pi. labial palpi ; pm. palp of the first 



cofrrYionfc TTI ^o^ 4-V.^ P air of maxillae ; prg. paraglossa ; sm. submentum; 



segments. In eacn tne ^ m . stipes of the flrst ma xiiia3, (From Lang.) 



