Prof. 0. Heer on the House Ant of Madeira, 329 



The head is somewhat larger than the abdomen ; it is alto- 

 gether shining, smooth, and naked. The point of insertion of 

 the antennae is also marked by a pretty deep groove, and the 

 anterior border of the forehead likewise furnished with an im- 

 pression ; on the other hand, the striae, which in the females as 

 well as in the soldiers are perceived on the head, are wholly 

 wanting. The mandibles (fig. iv. 3) are proportionably longer, 

 but more attenuated at the base than in the female and soldier, 

 acquiring thus a more slender form ; the two teeth at the point are 

 longer and much more acute, and the whole inner edge is set with 

 a row of little teeth, varying in number between ten and twelve. 

 These teeth are very regularly placed, and give a serrated ap- 

 pearance to the edge of the mandible. The teeth of both 

 mandibles fit into each other, and make it intelligible how these 

 little animals can hold and carry with their mandibles such 

 considerable loads. The other parts of the mouth are formed as 

 in the female. The antennae (fig. iv. 4) are much longer in 

 proportion than in the female and soldier ; their shaft or pedicle 

 extends conspicuously beyond the head, their base; in other 

 respects their structure is the same. The ocelli are wanting. 



The thorax is very narrow ; the prothorax (the collar) is very 

 finely granulated. The mesothorax is somewhat widened in the 

 middle ; it is quite smooth and shining ; on the other hand, the 

 scutellum and the metathorax are very finely granulated (only 

 perceptible under the microscope), the latter furnished on each 

 side with a small spine. 



The legs are formed like those of the female, only much 

 smaller (fig. iv. 5, 7) ; their tarsi are extremely fine, with how- 

 ever sharp claws, between which is seen a membranous lobe 

 (fig. IV. 6). They are finely pubescent. 



The second joint of the abdominal pedicle is proportionably 

 longer and more slender than in the female ; the abdomen itself 

 very small and shortly oval. The first segment is about half 

 the length of the whole, and is also much greater than the 

 second. 



The head is sometimes lighter, sometimes darker brown ; the 

 thorax, shaft of the antennae, femur and tibia light yellow-brown ; 

 the flagellum of the antennae and the tarsi light yellow. The 

 shining abdomen chestnut-brown, lighter at the base and tip. 



4. The Soldier, 



Fig. m. 1, natural size ; fig. iii. 2 & 3, magnified ten times. 



Whole length 2 lines ; length of head f of a line, breadth 

 full I line. Length of thorax f line ; of abdomen i line, breadth 

 the same. 



Distinguished from the labourers by the head being twice as 



