PHYLUM ARTHROPODA 



(521 



the gentr, 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 or 

 facets, like those in the 



eye of the Crayfish. 



Borne in sockets just 



below the eyes are the 



long, slender, highly 



mobile feelers or an- 



tcniuc, each made up 



of a large number of 



small segments, the 



first three being larger 



than the others. In- 

 ternal to the base of 



each antenna is a 



rounded white space 



— the fenestra — the 



nature of which is not 



known, but which- may 



be an abortive repre- 

 sentative of the simple 



eyes or ocelli found in 



most Insects. 



Movably articulated with the lower or ventral end of the 



clypeus is a broad plate, the labrum or upper lip (Fig. 492, Ibr.) 



overhanging the aperture of the 

 mouth. Below the genae and arti- 

 culating with the sides both of the 

 epicranium and of the clypeus are a 

 pair of stout mandibles (Fig. 492, 

 md., and 493, man.) which work 

 rerv horizontally like those of the Cray- 

 fish ; their inner edges are divided 

 into a number of teeth. Behind 

 the mandibles are a more flexible 

 pair of jaws — the first pair of maxilla 

 (mx. 1 , max. 1 ). Each maxilla exhibits 

 a structure comparable to the funda- 



Fl °^ ra l^ P o^et.X^ n a a P : mental type of the appendages of 

 pendages. etn. one of the cervical the Crayfish : — a basal part or proto- 



sclerites ; ey. eye ; gen. gena ; man. ■ •• • . • t> J~ 



mandible ; niaj., first pair of max- p/Mlte, Consisting 01 tWO Segments 



fj&S?" sec ° nd ■* ° f maxllla; (podomeres), supporting an internal 



mx, 



Fio. 402.— Mouth parts of "the Cockroach. Ibr. labrum ; 

 m. mentum ; md. mandible ; mxA. anterior pair of maxilla' :, 

 rue. and mi. outer and inner divisions of the first and 

 second pair of maxilla; ; nueg. second maxilla;; pi. labial 

 palp ; pui. maxillary palp ; xt. stipes ; urn. submentuin. 

 (From Lang's Comparative Anatomy.) 



