ORDER H7MENOPTERA. 



171 



reasoning powers to meet the exigencies of their life; their ordi- 

 nary acts being instinctive, viz., the results of inherited habits. 

 Typical genera are Camponotus, Polyergus, Formica, Myrmeco- 

 cystus, and Tapinoma 



Family Odontomachidse. Mandibles very long and suddenly re- 

 curved within at tip, inserted close to each other. Odontoniachus. 



Family Dorylidas. Ants with a very small or even indistinct 



FIG. 218. Eciton mexicana; worker-major; a, front view of head. 



clypeus; frontal crest very short; petiole depressed, nodiform. 

 Represented by a single genus, Labidus, of which only the males 

 are known; and they are supposed to be the males of Eciton. 



Family Poneridae. Abdomen proper constricted between the first 

 and second segments. Pouera. 



Family Myrmicidae. In the stinging ants the petiole consists of 

 two joints. Myrrnica molesta Say is found all over the world; other 

 typical genera are Atta, Eciton, Pseudomyrma, Pogonomyrmex, 

 and Pheidole. The workers are divided into two sets; those with 

 large heads are called worker-majors or soldiers, and the smaller ones 

 worker-minors. 



The group of Fossores, or fossorial Hymenoptera, consist- 

 ing of the sand- and wood-wasps, etc., is divided into a 

 number of families, some of which may yet be united. The 

 petiole is simple, i.e., not formed into scales or nodes; there 

 are no workers, though the females of the Mutillidge are 



