NOTES ON MEXICAN ANTS. 59 
On this point but little is recorded as yet in this country,* 
but we have abundant testimony from observers of European 
species. 
The major workers are usually of large size, and have the 
head greatly developed, but are comparatively few in num- 
ber. Their duties in the society are not clearly understood, 
but they are supposed to have some kind of superintendence 
over the rest. 
In the following descriptions I have thought best only to 
mention one or more of the prominent external characteris- 
tics by which the genera of the species here mentioned may 
be known. t 
; SUBFAMILY FORMICIDÆ. 
In the genus Formica, the node, or knot-like segment 
between the thorax and abdomen, forms a smooth, oval or 
globular mass, and there is no sting. 
Formica esuriens Smith. “This is very common in Ori- 
zaba and Cordova. It lives in great numbers in dead trees, 
in which it tunnels galleries, or under stones.” From its 
form this should be grouped with our large black Formica 
Pennsylvanica, which lives in dead trees. It is not by 
any means certain that the species living in dead wood per- 
forates that which is living. It seems much more likely 
that it occupies the channels already opened by the grubs of 
various borers, and helps to complete the work partly done 
for it. In this region the worker remains in a torpid state 


- *See Mr. J. A. Allen’s “ Notice of a Foray of a oy, of Formica sanguinea La- 
treille, upon a Colony of the black species of Formica, for the purpose of making 
Slaves of the latter.” Proceedings of the Essex Institute, Vol. V, p: l, 1866. 
Formicidæ. has b 
1e Ant-family, Fe having the 


icide. fi t of the abd ing a single node. (See Fig.3 a, 
showing the pape node cor Polyrhachis) Not pro nae wana sting. 
Poneride.— The segment of the abdomen with one node. Provided with a 
sting. 
Myrmicide.— ment of the ‘abdomen with two nodes. Provided 
sting. From this Sakis two more subfamilies have been eren Attidæ, the 
workers ve enormously developed | heads, and i , 
1 tha 


Caus or p Ve a3! liy or p - 
