ANNULOSA: insecta. 



2SI 



that, namely, of a second pair of maxillae, is more or less per- 

 fectly retained by the Orthoptera and some of the Neuroptera. 

 The lower or basal portion of the labium is called the " men- 

 tura " 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." 



Fig. 84.— Organs of the mouth in Insects, i. Trophi of a masticating Insect (Beetle): 

 a Labrum or upper lip ; b Mandibles ; c Maxillse with their palpi ; d Labium or 

 lower lip with its palpi. 2. Mouth of a Butterfly: tfEyei^Base of antennae;^ 

 Labial palp : ^ Spiral trunk or "antlia." 3. Mouth of a Hemipterous Insert (i^/^/a 

 cinerea) : / Labium : 7;; Maxillae ; « Mandibles. 



In the typical suctorial mouth, as seen in the Butterflies 

 (fig. 84, 2), the following is the an-angement of parts : — The 

 labrum and the mandibles are now quite rudimentary ; the 

 first pair of maxillse is greatly elongated, each maxilla forming 

 a half-tube. These maxillse 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 anterior of each maxilla, and the third formed 

 between t"hem by their apposition. To the base of the trunk 

 are attached the maxillary palpi, which are extremely small. 

 Behind the trunk is a small labium, -composed of the united 

 second pair of maxillse. The " labial palpi " are greatly devel- 

 oped, and form two hairy cushions, between which the trunk 

 is coiled up when not in use. 



In the Bee there exists an intermediate condition of parts, 

 the mouth being fitted partly for biting and partly for suction. 

 The labrum and mandibles are well developed, and retain their 



