572 



ZOOLOGY 



SECT. 



of its generalised structure, which makes it a fairly central 

 member of the class, devoid of any extreme modifications. 



Three regions are very distinctly recognisable in the body of 

 the Cockroach. In front is the head, elongated vertically, bearing 

 the very long slender feelers and the large eyes, and contracted 

 behind to form a narrow ncclc. In the middle is the thorax, 

 consisting of three segments bearing the three pairs of legs and 

 the two pairs of wings. Behind is the !,</<, men, consisting of ten 

 segments covered over above by the wings. The entire surface 

 is covered by a chitinous cuticle, which is specially thickened on 

 the head, on certain parts of the thorax, and in the anterior pair 

 of wings. 



The head consists of four parts the cpicranium behind, com- 

 prising the region between and behind the eyes, and the dypeus, 



Kic.. 4.:.:3. Periplaneta americana. Male, dorsal view. Natural size. 



or portion extending vertically downwards, with two lateral 

 parts, the gence, in front. The eyes are a pair of reniform black 

 patches on the sides of the head : each is seen when examined 

 with a lens to be divided into a number of minute hexagonal areas 

 in'fcctx, like those in the eye of the Crayfish. Borne in sockets 

 just below the eyes are the long, slender, highly mobile feelers or 

 lat/ennce, each made up of a large number of short segments, the 

 first three being larger than the others. Internal to the base of 

 each antenna is a rounded white space the fencstru the nature 

 of which is not known, but which may be an abortive representa- 

 tive of the- simple eyes or t>r<lli found in most Insects. 



Movably articulated with the lower or ventral end of the 

 clypeus is a broad plate, the loin-tan, or upper lip (Fig. 454, lbr.\ 

 overhanging the aperture of the mouth. Below the gense and 

 articulating with the sides both of the epicranium and clypeus 



