THE HEAD. 11 
they differ also in the number of facets. Thus, again 
following the same authority, the large workers of 
Camponotus ligniperdus have 500, the smaller ones 
only 450; while in the Harvesting ant (Atta barbara) 
the contrast is even greater, the large specimens 
having 230, the small ones only from 80 to 90. The 
ordinary workers have in Polyergus rufescens about 
400 ; in Lasius fuliginosus, 200; in Tapinoma erra- 
ticum, 100; in Plagiolepis pygmea, 70 to 80; in 
Lasius flavus, about 80; in Bothriomyrmex meri- 
dionalis, 55; in Strongylognathus testaceus, Stenamma 
Westwoodii, and Tetramorium cespitum, about 45 ; 
in Pheidole pallidula, about 30; Myrmecina La- 
treillei, 15; Solenopsis fugax, 6 to 9; while in Ponera 
contracta there are only from 1 to 5; in Eciton only 1; 
and in Zyphlopone the eyes are altogether wanting. 
The number of facets seems to increase rather with 
she size of the species than with the power of vision. 
The ocelli are never more than three in number, 
disposed in a triangle with the apex in front. Some- 
times the anterior ocellus alone is present. In some 
species the workers are altogether without ocelli, which, 
however, are always present in the queens and in the 
males. 
The mouth partg are the labrum, or upper lip ; the 
first pair of jaws or mandibles; the second pair of jaws 
or maxillz, which are provided with a pair of palpi, 
or feelers; and the lower lip, or labium, also bearing 
a pair of palpi. 
