24 Riley Presidential Address. 



tropical countries. Some two hundred species have already been 

 described from North America, many of which are nearly related 

 to or even identical with those of Europe; while some are cosmo 

 politan, having been distributed by the agency of man over almost 

 every part of the world. One of the best known of these cosmo 

 politan forms is the the little Red Ant, Monomormmpharaani* 

 Linn., a grievous household pest. Under the tribal term Heter- 

 ogyna Latreille, the ants are divided by the later systematists 

 into four families (by some considered sub-families), namely, the 

 Formicidae, the Poneridae, the Dorilidae and the Myrmicidse. The 

 first family, Formicidae, comprises all those species which are des 

 titute of a sting, except in the genus (Ecophylla, and are further 

 characterized by having but one node or scale connecting the ab 

 domen with the thorax, and by the habit in the larva of construct 

 ing for pupation, a dense, smooth, ovoid, silken cocoon. The re 

 maining families are possessed of a sting, the Poneridae agreeing 

 with the Formicidae in the cocoon-forming habit of the larva and 

 in having but a single node or scale connecting the thorax and ab 

 domen, but having an additional, more or less pronounced con 

 striction between the first and second abdominal joints. The 

 Dorilidae are somewhat aberrant, the female and worker, so far 

 as known, being blind, and nothing being yet known of their 

 larvae. In the last family, the Myrmicidae, there are two well- 

 developed, freely mobile nodes between the abdomen and the 

 thorax, and the larvae are unprotected by any cocoon during 

 pupation. The most interesting and destructive species occur 

 in this family. 



Let us glance briefly at some of the species, more according to 

 habit, however, than this classification, and preferably our North 

 American species. Thus they may be considered as Carpenter, 

 Mound-building, Harvesting, Honey, Leaf -cutting, Nest- building 

 and Driving or Foraging ants. (Note 5.) 



Ant Economy and Habits. 



ANT WARS. Very many most interesting accounts of the intel 

 ligence and battles, and of the curious persistency of ants, espec 

 ially of the foraging species, are recorded by travellers in tropical 

 countries, and particularly by the late Henry Walter Bates in 

 his " Naturalist on the River Amazons ". It is a well established 

 fact that ants, like human beings, do at times declare war against 



