THE EXTERNAL STRUCTURE OF ANTS. 



They are used for excavating soil or wood, cutting up the food, righting, 

 carrying the prey, their young or one another, and in some species, 

 even in leaping by closing them rapidly against hard bodies. Ants are 

 remarkable in being able to open and close their mandibles indepen- 

 dently of the maxillge and labium. These organs, which lie underneath 

 the small and vestigial labrum and close the mouth completely except 

 when the insect is feeding, have a complicated and interesting structure. 

 The maxillae ( Fig. 5, B,D) are paired and each consists of the following 

 pieces, or sclerites : the hinge (cardo), the stem (stipes), the maxillary 

 palp, which may be from 



I 6-jointed, an inner ' 



blade (lacinia) and an 

 outer blade, the galea. 

 The galea bears a row 

 of gustatory papillae and 

 a row of bristles which 

 are used in cleaning the 

 legs and antennae. The 

 lacinia is membraneous 

 and toothless and shows 

 that the ant feeds on 

 liquid substances only. 

 This is also proved by 

 the structure of the 

 labium (Fig. 5, O, 

 which consists of the 



following sclerites : 



the 



hind chin (submehtum), 

 the chin (mentum) and 

 the tongue (glossa), all 

 unpaired, and the labial 

 palpi, consisting of 

 from one to four joints, 

 the paraglossae and hy- 

 popharynx, which are 

 paired. The tongue, 



B 



FIG. 5. Mouthparts of Myrmicu nibra. (Janet.) 

 A, Seen from the lower, or ventral side, in situ ; />' 

 and D, maxilke ; C, labium, seen from the upper, or 

 dorsal side, detached ; a, mandible ; b, maxilla ; c, 

 mentum ; d, maxillary palp ; e, labial palp ; /, glossa, 

 or tongue; g, adductor muscle of mandible; /;, abduc- 

 tor muscle of mandible ; i, labium ; k, gustatory 

 organs; /, duct of salivary glands; m, maxillary 

 comb ; n, gular apodeme. 



with which the ant rasps 



off or laps up its liquid or semi-liquid food, and cleans itself and 

 its fellows, is a protrusible, elliptical pad, covered with fine trans- 

 verse ridges. At its base lies the opening of the salivary duct. The 

 paraglossse are small sclerites beset with rows of bristles. The 

 hypopharynx, which is less developed than in some of the other 



