APPENDAGES. 



621 



the mentum, while the part corresponding with the galea 

 of the 1st maxillae is often termed the paraglossa, median 

 to which, when it exists, is the lacinia. Each second maxilla 

 normally bears a palp. The complex formed by the fused second 

 maxillae is often termed the labium or lower lip (Fig. 375). All 

 the parts may undergo profound modification. The Hemiptera 

 have their labia modified to form a jointed sheath in which the 

 stylet-like mandibles and 1st maxillae lie, the labial palps 

 are reduced (Fig. 375). In the Diptera the labium is also said 

 to form a grooved proboscis and the palps persist. In many 

 Hymenoptera the mentum is drawn out into a long narrow 

 structure (Fig. 374). 



The mandibles, and the first and second maxillae are often re- 

 ferred to as the mouth-parts or trophi. The homologies of these 

 parts in the several Orders is a matter of some divergence of 

 opinion and the whole subject would well repay a thorough 

 revision based on embryological research. 



The seventh, eighth and ninth (eighth, ninth and tenth accord- 

 ing to Folsom) segments always take part in the formation of 

 the thorax and, in the case of the Hymenoptera, the first 

 abdominal is 

 pushed forward 

 and included in 

 this tagma. The 

 appendages of 

 the first three are 

 legs, and these 

 three pairs of 

 legs, confined in 

 the imago to the 

 three typical 

 thor a c i c s e g - 

 ments, are very 

 characteristic of 

 Insects. The 

 legs are usually 

 described as con- 

 sisting of the fol- 



Inwinrr e^rrorfe FlG - 377. Different form of legs (regne animal), a Mantis 

 with predatory leg ; b leg of Carabus used in running ; c of 



Wf-ViA rf\vn Q Acridium used in springing ; d of Gryllotalpa used in digging ; 



COXa } a e swimming-leg of Dutiscus. 



