MEXICAN HYMENOPTERA. 4o 



sun and hazard themselves to bear their power only during the time nv- 

 cessary to traverse a clearing or a road. 



No. 36 of my collection is quite common in the State of Vera Cruz, 

 from the shore as far as the environs of Orizaba. It presents, among 

 the neuters or workers which compose its societies, at least three cate- 

 gories of individuals; 1st, Those of great size f workers majores of 

 Smith), having the head much enlarged and armed with mandible.-^, 

 prolonged, slender and recurved into a hook: 2nd, Those of a size al- 

 most equal to the preceding, with little or no enlargement of the head, 

 and the mandibles yet slender, but not also recurving toward the base. 

 Among them, as in the first division, the head and the thorax are of a 

 lighter color than the rest of the body. 3rd. The third category (work- 

 ers minores of Smith) comprehends the individuals having the head 

 and mandibles normally developed, and the color uniform. Among 

 them the size is quite variable, they never attain to that of the two 

 first divisions. 



It is almost impossible to determine, with any certainty, the numeri- 

 cal proportion which each one of these three categories of workers bears 

 in the colony ; the following, based on a good number of observations, 

 may give an approximate idea of it. 

 Workers majores, 

 " intermedii 

 " minores 



This determination is so much the less easy to establish, because there 

 often comes a column of these tepec/nas, only composed of individuals 

 of the two last cla-sses. This ordinarily takes place when it goes forth 

 on a hunting expedition, in which the workers with long mandibles 

 rarely take part. 



A similar difficulty presents itself when one undertakes to divine 

 the role of each one of these divisions of workers in the labors of the 

 community. I incline to think that those of the first class (workers 

 majores) use in the interior of the nest, for the labors of piercing the 

 galleries, of clearing away, the instruments which the enormously de- 

 veloped head and mandibles furnish them. To these is reserved, with- 

 out doubt, the guard of the forniicarium during the expeditions under- 

 taken by the two other classes. That which takes place in the socie- 

 ties of the arriero ant {Orcodoma nic.cicaiio) seems to me to favor this 

 conjecture. Among these ants, in fact, the large sized workers having 

 great heads provided with a single ocellus, do not quit the nest at all 

 and do not go forth to the light, except when, troubled or alarmed by 



