MEXICAN UYMENOPTERA. 45 



A. Metathorax more or less spinosc. 



1. Three classes of workers. Worker major with long niandiljles. 

 Xo. fi8. Eciton hamata, Fahr. 



All classes have the head white and shining and the remainder of 

 the body whitish-ferruginous. The antennae are subfiliforni. 



This is abundant in Panama and Brazil. 

 No. ."ifi. Eciton mexicana, Gue'r. 



In the major and intermediate workers, the color of the head is pale 

 brown, the thorax ferruginous and the abdomen nearly black. In the 

 minor workers the head and whole body are black, with ferruginous 

 tints. This closely resembles the E. hamata, but differs as follows : 

 The antennae are longer and the joints of the flagellum longer and more 

 slender. The mandibles of second and third workers are in hamata 

 aciculate longitudinally and toothed on the inner edge ; in me.ricana 

 not aciculate longitudinally and with the biting edge smooth. The 

 spines or angles at the back of the head of hamata are acute and curv- 

 ed outwardly. In this they are not acute. The spinose points on the 

 metathorax of hamata are the termination of rather prolonged side ca- 

 rinse. In this the carinte are shorter and less prominent. In hamata 

 the first node is one-half longer than wide ; in this it is nearly as wide 

 as long. 



2. Two classes of workers, none with long mandibles yet taken. 



Xo. o. Eciton rapax, Smith. ^=brunnea, Norton, Am. Nat. II, 1868, p. 62. Proc. 

 Essex Inst. 



The antcnnge are intermediate between No. 68. and 3G, the mandi- 

 bles coriaceous above, with their biting edge irregularly toothed and a 

 large tooth towards the apex. The spines at the back of head are like 

 those of hamata. of the metathorax longer. The color of the head and 

 thoi'ax blackish-brown, of the abdomen a clear brown. 



This is found also in Brazil. 

 No. 39. Eciton crassicornis. Smith. 



The color of this is a dull, dark reddish-brown, abdomen shining. 

 Antennte short, thickened, scape clavate, all the joints of the flagellum 

 short, from middle to apex wider than long, paler beneath. 



This is found in Brazil. 



B. Metathorax unarmed with spinose processes. 



a. Back of head widely emarginate, with acute angles. 

 No. 40. Eciton Sumichrasti, Norton, Am. Nat. II, 1808, 62. Proc. Essex Inst. 



This is remarkable in having the back of head nearly as wide as the 

 middle, the head, thorax and nodes very rugose and the abdomen pol- 

 ished. But one size of workers yet examined. 



