Heterogyna and Fossorial Hijmenoptera. 203 



the Poneridae and Myrmicidse are aculeate. The j^upas 

 of Formica and Ponera are generally contained in silken 

 cocoons ; those of the Myrmicidae are always naked. 

 All the species possess three sexes, c? , ? , and ^ . The 

 <? and ? have wings ; the ^ is always apterous ; the 

 wings of the ? are pulled off by the ^ or cast, after impreg- 

 nation. 



(4) 1. Petiole with a single transverse scale or node. 



(3) 2. Abdomen not constricted between tlie 1st and 



2nd segments ; J and ^ without a sting . . Furmicida. 



(2) 3. Abdomen constricted between the 1st and 2ud 



segments; 5 and ^ with a sting .. .. Poneridcc. 



(1) 4. Petiole with two nodes . . . . . . . . Myrmicidcc. 



FOEMICID^. 



(4) 1. Petiole with an erect scale. 



(3) 2. ^ 1st joint of flagellum not thicker than the rest; 

 5 and 5 with the 1st joint of the flagellum as 

 long as or longer than the apical. . .. .. Formica. 



(2) 3. ^ 1st joint of flagellum much thicker than the 

 rest; J and ^ with the 1st joint of the flagellum 

 shorter than the apical . . . . . . . . Lasius. 



(1) 4. Petiole without an erect scale . . . . . . Tapinovia. 



Formica, Linn. (PI. VII. figs. 1 and 2). 

 Syst. Nat. ed. x. vol. i. p. 579. 



<? and ? about equal in size ; ^ very variable in this 

 respect, the ^ major, as it has been called, being often 

 more than half as large again as the ^ minor. Pupae 

 enclosed in silken cocoons ; ? and ^ without stings. 

 Maxillary 2)alpi with six joints, labial with four. Antennae 

 13-jointed in tlie(?, 12-jointed in the? and ^ . Man- 

 dibles generally somewhat slender in the ? , wide and 

 triangular in the ? and ^ , much narrowed at the base. 

 Upper wings with one marginal, two submarginal, and 

 one discoidal cells, the apical margin of the 2nd sub- 

 marginal being the actual edge of the wing. Petiole with 

 an erect, flattened scale, generally more or less triangular, 

 widest above. 



The species of this genus are rather naturally divided 

 into two sections by their habits, the first four making 

 their nests above ground, the last three underground. 



Messrs. Emery and Forel consider the last three to be 

 all races of one species. 



TRANS. ENT. SOC. 1880. — PART IV. (DEC.) T 



