624 



ZOOLOGY 



SECT. 



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

 Crustacea in never being provided with a palp. An arrangement 

 of the mouth-parts adapted for biting or chewing has already been 

 described in the case of the Cockroach : this type is characteristic of 

 the order Orthoptera, to which the Cockroach belongs, and a very 

 similar type characterises the Coleoptera. In the Hymenoptera 

 (Fig. 527) the mouth-parts are adapted both for biting and for 

 licking; the mandibles (md.) and maxillae (mx^) are sharp and 

 lancet-like ; the middle part of the labium is produced into a long 

 median tongue (ligula, li.) at the sides of which are a pair of 



accessory tongues or para- 

 glossoB (prg.). In the Hemi- 

 ptera there is a proboscis 

 formed from the labium 

 and enclosing the stylet-like 

 mandibles and maxillae . In 

 the Diptera (Fig. 528) 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 (inx. 2 ) enclosing a 

 spine or seta (hp.) which 

 is a process from the hypo- 

 pharynx and sometimes 

 stylet-like maxillae (mx.^. 

 In the Lepidoptera 

 (Fig. 529) the mandibles are 

 aborted in the adult, and the 

 maxillae are developed into, 

 elongated half-tubes, which 

 when applied together form 



FIG. 529. Mouth-parts of the Lepidoptera. B, the Q r> nrn W P fn"h (0* '\ pa-neKlo 



second maxilla). Lettering as in preceding figures : a Complete tUDe (ST.) CapaDle 



pi. labial palp ; pm. palp of the anterior maxillae ; o f being coiled UP in a Spiral 

 sr. sucking tube. (Prom Lang.) -. .fi -i -, 



manner under the head, the 



extremity provided with hooks or spines for rupturing the nectaries 

 of flowers. 



Appendages of the thorax. Each of the segments of the 

 thorax bears a pair of five-jointed legs ; the terminal section or 

 tarsus being made up of a number of short segments, usually five, 

 and ending in a pair of claws, often with an adhesive pad or sucking 

 disc between them, or in a single claw. In accordance with varia- 

 tions in the uses to which they are put, considerable differences are 

 observable in the form of the legs in different groups of Insects. 

 In most they are adapted for walking, and are long and slender ; 

 in some they are expanded to enable them to act as swimming 



