ANNTJLOSA : LNSECTA. 



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In the Masticatory Insects, such as the Beetles (fig. 62, 1), 

 the trophi consist of the following parts, from before back- 

 wards : (1) An upper lip, or 'labrnm,' attached below the 

 front of the head. (2) A pair of biting jaws, or ' mandibles.' 

 (3) A pair of chewing jaws, or 'niaxilke,' provided with one 

 or more pairs of ' maxillary palps,' or sensory and tactile 

 filaments. (4) A lower lip, or ' labium,' composed of a 

 second coalescent pair of maxillae, and also bearing a pair 



Fig. 62. Organs of the mouth in Insects. 1. Trophi of a masticating Insect 

 (Beetle) ; a. Labrum or upper lip ; b. Mandibles ; c. Maxillae with their 

 palpi ; d. Labium or lower lip with its palpi. 2. Mouth of a Butterfly ; 

 o. Eye ; /. Base of antenna ; g. Labial palp ; h. Spiral trunk or 

 ' antlia.' 3. Mouth of a Hemipterous insect (A'epa cinerea) ; I. Labium ; 

 m. Maxillas ; n. Mandibles. 



of palpi, the ' labial palps.' The lower or basal portion of 

 the labium is called the 'mentum' or chin, whilst the upper 

 portion is more flexible, and is termed the ' ligula.' The 

 upper portion of the ligula is often developed into a kind of 

 tongue, which is very distinct in some Insects, and is termed 

 the ' lingua.' 



In the typical suctorial mouth, as seen in the Butterflies 

 (Jig. 62, 2), the following is the arrangement of parts. The 

 labrum and the mandibles are now quite rudimentary; the 

 first pair of maxillae is greatly elongated, each maxilla forming 

 a half-tube. These maxillas adhere together by their inner 

 surfaces, and thus form a spiral 'trunk,' or 'antlia' (inappro- 

 priately called the ' proboscis '), by which the juices of flowers 

 are sucked up. Each maxilla, besides the half-tube on one 

 side, contains also a tube in its interior; consequently on a 

 transverse section the trunk is found really to consist of three 

 canals, one in the interior of each maxilla, and the third formed 



