



BRITISH ANTS. 



small space, usually triangular in shape, which is called the frontal 

 area ; and behind this an impressed longitudinal line, the frontal 

 furrow, is often present, which runs back towards the base of the 

 head. The front is the region lying between the frontal carinae (a 

 pair of ridges, situated on the inner side of the insertion of the 

 antennae), and is bounded anteriorly by the clypeus. Posteriorly 

 it passes indefinitely into the vertex of the head and the temples ; 

 the latter lie above and behind the eyes. The occiput is the short 

 region between the vertex of the head and the narrow opening 

 (the foramen) beneath at its junction with the thorax. 



The ventral surface of the head between the labium and the 

 above-mentioned opening is the gula or throat, it is generally 

 divided by a longitudinal suture. 



Mandible 



Maxillary 



palpus 

 Tongue 

 Maxilla 

 Labial palpus 



Foramen 

 Fig. 2. Underside of head of Formica pratensis ^. 



The compound or lateral eyes are situated on either side of the 

 head ; the simple or median eyes, stemmata, or ocelli, when present, 

 are three in number, and are placed triangularly on the front of the 

 head. Both kinds of eyes are most highly developed in the males, 

 and least in the workers, the ocelli being wanting in the latter of 

 some species. 



The facets of the compound eyes vary greatly in size and number 

 in different species. It has been estimated that the lateral eye in 

 the worker of Ponera punctatissima only consists of one facet ; in 

 the worker of Solenopsis fugax from 6-9, in the female 200, and in 

 the male 400 ; Tapinoma erraticum worker 100, female 260, 

 male 400 ; Formica pratensis worker 600, female 830, male 1200. 



The mandibles are very variable in structure, being sometimes 

 long, narrow and pointed, but often broad and massive, having 

 three borders, an external, an internal, and a terminal, the latter 



