LEPT^OTHORAX. 145 



diverse, and they live in small communities nesting under stones, 

 in the ground, under bark, in moss, in hollow twigs, in rotten 

 branches, in galls and fallen nuts, in the borings of other insects, 

 and between the laminae of stones, etc. 



The queens are very little larger than the workers, at least in 

 the large species, and their habits are very similar, both the winged 

 and dealated females carrying about the larvae and pupae in their 

 mandibles. 



There is generally more than one fertile female in the same 

 colony, and sometimes the virgin females remove their own wings 

 without leaving the nest. The marriage flight is similar to that of 

 the genus Myrmica, but too few males and females occur to enable 

 it to be called a swarm. 



A number of intermediate forms between the females and 

 workers frequently occur, and both microgynes and ergatoid 

 females are often present in the same colony with typical females. 



When one of the workers is carried by another, it is seized by 

 the mandibles and swung over the back of the carrier, with the 

 dorsal surface uppermost. 



These ants do not keep Aphidae in their nests, nor do they 

 appear to seek them on plants, but they lick the leaves of trees 

 and plants on which honey-dew has fallen. 



Many species have a tendency to enter into more or less close 

 symbiotic relations with other ants. 



This is the only genus in which the ants are furnished with blunt 

 hairs, which have been called " clubbed hairs," but which in any 

 case are never pointed. 



Wheeler designated Formica acervorum Fabricius as the type of 

 the genus Leptothorax [Ann. New York Acad. Sci. 21 166 (1911)], 

 but Emery [Ann. Soc. Ent. Belg. 56 271 (1912)] selects L. dypeatus 

 Mayr, both because it was the first species described by Mayr, and 

 because L. acervorum Nylander has already been made the type of 

 the subgenus Mychothorax by Ruzsky. 



^ Head oblong, rounded posteriorly ; clypeus triangular, concave or 

 convex, transverse anteriorly ; frontal carinae short, almost straight ; frontal 

 area somewhat impressed, not clearly defined ; mandibles broad, terminal 

 margin armed with four or five teeth ; maxillary palpi five- jointed ; labial 

 palpi three-jointed ; antennae eleven-, or twelve-jointed, first joint, and last 

 three joints of funiculus longer than broad, the latter forming a distinct club 

 about as long as the rest of the funiculus, its last joint being equal in length 

 to or a little longer than the two preceding taken together. Thorax long and 

 narrow ; pronotum rounded anteriorly ; suture between pronotum and meso- 

 notum wanting, between mesonotum and epinotum marked, or wanting ; 

 epinotum armed with two teeth, or spines. Petiole cylindrical anteriorly, 

 nodiform posteriorly ; post-petiole nodiform ; gaster oblong oval ; sting 

 large. 



The body is furnished with short, scattered, blunt hairs. 



$ Very like the ^ ; gaster longer oval. Wings very pale ; fore-wings with 

 one cubital cell, and one discoidal cell. 



<J Head triangular ; mandibles narrow, flat, unarmed, or furnished with 



