XXVI INSECTA : HYMENOPTERA 405 



parts, and a pair of lateral soft jaws or maxillae, each pro- 

 vided with a palp and a row of bristles with which the 

 antennae and legs are cleaned. Below the mouth is the 

 labium, also bearing a pair of palps, and a median lobe or 

 tongue with which the ant licks up food and cleans itself 

 and its charges; the duct of the salivary gland opens at 

 the base of this tongue. Just below the mouth and above 

 the lower lip is a little sac-like cavity (the infra-buccal 

 sac) which opens close to the mouth (for its use see p. 411). 

 The thorax consists of the usual three segments, fused with 

 one abdominal segment, as explained on p. 362. Underneath 

 the three thoracic segments are attached 

 the three pairs of jointed legs always 

 found in insects, and three spiracles 

 are present on either side. The legs, f^^ru 



as usual in insects, have four joints and 

 then the five-jointed foot (tarsus), the 

 basal joint of the tarsus being un- 

 usually long (Fig. 311). There is a ^^ 3 tarsus, 

 little projecting spur between the tibia 

 and tarsus of each leg, and on each 

 front leg this is specially large and ^'°;1^^-:;;^!'^^TM'*^ 



, , ° , , '^ •' ^ . of the Yellow Meadow 



movable, and has a concave inner ^nt. 



surface beset with a row of stiff 



bristles, which faces a similar concavity set with bristles on 



the first tarsal joint. This structure is known as the " strigil " 



(Fig. 311), and is used in cleaning the antennae and back 



legs which are drawn between the bristled surfaces. 



The, Abdomen. — This term is generally taken to refer only 

 to the swollen hind body or gaster, though, as has been 

 mentioned, part of the true abdomen is really fixed to the 

 thorax, and as in all ants, the hind body is separated from 

 the "thorax" by a much -constricted stalk or "pedicel" 

 formed of one abdominal segment in Lasius, but of two 

 in many ants (see classification, pp. 426-7). Five segments 

 can be seen externally on the " gaster " when viewed from 

 the side, but only three can be clearly seen from above. Three 

 more segments are to be made out by dissection, but are 

 hidden in life. In many species of ants there is at the 

 end of the abdomen, in both workers and queens, a sting 

 formed of a pair of needle-like, smooth styles surrounded by 



