XI 



PHYLUM ARTHROPODA 



589 



The antenna? vary in shape in different groups, and sometimes 

 even in the sexes of the same species. They are sometimes taper- 

 ing, sometimes moniliform, sometimes club-shaped, sometimes 

 pectinate, sometimes plume-like. In addition to functioning as 

 tactile appendages they bear the olfactory sets. The mandibles 

 are always one-jointed, and differ from those of the Crustacea in 

 never being provided 

 with a palp. An arrange- 

 ment of the mouth - 

 parts adapted for biting 

 or chewing has already 

 been described in the 

 case of the Cockroach. 

 This type is character- 

 istic of the order Or- 

 thoptera, to which the 

 Cockroach belongs, and 

 a very similar type char- 

 acterises the Coleoptera. 

 In the Hymenoptera 

 (Fig. 478) the mouth 

 parts are adapted both 

 for biting and for licking 

 and sucking ; the mandi- 

 bles (md.) and maxilla? 

 (MjA) are sharp and 

 lancet-like, the middle 

 part of the labiuni is 

 produced into a long 

 median tongue (ligula, 

 li.) at the sides of which 

 are a pair of accessory 

 tongues or paraglossce 

 (prg.}. In the Hemip- 

 tera there is a proboscis 

 formed from the labium 

 enclosing the stylet- 

 like mandibles and maxillae. In the Diptera (Fig. 479) the 

 mandibles (md.}, usually not developed in the males, are biting or 

 piercing organs, while the basal parts of the labium form a pro- 

 boscis (mx 2 .) enclosing a spine or seta (lip.\ which is a process 

 from the hypo-pharynx a chitinous process on the roof of the 

 mouth, and sometimes stylet-like maxilla?, (mo: 1 .). In the Lepidoptera 

 (Fig. 480) the mandibles are aborted in the adult, and the maxilla? 

 are developed into elongated half-tubes, which when applied 

 together form a greatly elongated tube (sr.) capable of being 

 coiled up in a spiral manner under the head, the extremity 



PIG. 478. A, mouth parts of the Honey-bee (Apis 

 mellifica); B, the two pairs of rnaxillte ; av, eye ; 

 a, antenna ; c. cardo ; cji. epipharynx ; Un: labrum ; 

 li. ligula ; m. meiituin ; mm.m$\ first pair of nmxilhe ; 

 m<i. mandible ; put, palp of the first pair of maxilla; ; 

 pry. paraglossa ; sin. submeiitum ; xtiu. stipes of the 

 first maxilla;. (From Lang.) 



