330 Prof. 0. Heer on the House Ant of Madeira. 



large, emarginate at the base and striated, by the shorter and 

 stronger mandibles, which are not toothed on their inner edge, 

 and by the somewhat larger abdomen. 



The faintly pubescent head is of enormous size, and much 

 more deeply emarginate at the base than in the female, so that 

 it is nearly heart-shaped. A deep longitudinal furrow traverses 

 it in the middle. The antennal clefts are pretty deep, being 

 bordered anteriorly and towards the forehead by a rather strong 

 prominent rim. The fore-part of the forehead has a deep im- 

 pression like that of the female. The clypeus is very short, and 

 divided from the head by a faint line. The upper side of the 

 head is finely striated longitudinally, as in the female; these 

 striae become obsolete behind the middle of the head, so that its 

 hinder part is quite smooth. The eyes are small, and the ocelli 

 are wanting. The trophi are as in the female, as are also the 

 mandibles, except that on their cutting edge stands a pair of 

 very small obtuse denticles furnished with a bristle (fig. iii. 4). 

 The antennae are as in the females ; their shaft is much shorter 

 than the head; the three last joints (tig. iii. 6, 7) are distinctly 

 separate. 



The thorax is similarly formed as in the labourer, except that 

 the mesothorax is much broader in the middle and bears on each 

 side a little tubercle (Harchen) furnished with a bristle, by which 

 structure it is distinguished both from the female and labourer. 

 The scutellum is almost quadrangular; the hinder piece of the 

 metanotum is armed on each side with a sharp spinule, and 

 furnished in the middle with a longitudinal cleft. The whole 

 thorax is sprinkled with scattered or distinct hairs. The legs are 

 larger than in the labourer ; otherwise they are of the same form. 



The abdomen is much smaller than the head. The first joint 

 of the pedicle is enlarged into a more prominent scale-like pro- 

 tuberance (furnished with a tuft of hairs) than in the labourer; 

 the second joint, on the other hand, is shorter and thicker than 

 in these, and approaches in form that of the female. The first 

 segment of the abdomen is the largest ; the second of about 

 the same breadth, but shorter ; the third rounded behind ; the 

 fourth is very small, and almost withdrawn into the preceding. 

 It is quite smooth and shining, sparingly sprinkled with fine 

 bristles, which at the hinder edge of each segment are longer 

 and set closer together. 



The head is sometimes lighter, sometimes darker brown ; on 

 the under side always lighter than on the upper. The edge of 

 the clypeus and the anterior edge of the mandibles black ; the 

 antennae and legs are light yellow ; the thorax and abdominal 

 pedicle somewhat lighter brown than the head ; the abdomen at 

 the base and tip of the same colour ; the second and third seg- 



