TIIK HKAH. 11 



they differ also in the number of facets. Thus, again 

 following the same authority, the large workers of 

 -motus ligniperdus have 500 V 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 rufcscens about 

 400 ; in Lasius fuliginosua, 200 ; in Tapinoma erra- 

 ficum, 100; in Plagiolepis pygmcea, 70 to 80; in 

 Lasius flaviis, about 80 ; in Bothriomyrmex meri- 

 dionali8,55 ; in Strongylognathus te8taceu8,Stenam,ma 

 Westwoodii, and Tetramorium ceepitum, about 45 ; 

 in Pheidole pattidula, about 30 ; Myrmtcina La- 

 treittei, 15 ; Solenopsis fugax, 6 to 9 ; while in Ponera 

 contracta there are only from 1 to 5 ; in Eciton only 1 ; 

 and in Typhlopone the eyes are altogether wanting. 



The number of facets seems to increase rather with 

 the size of the insect 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 parts are the labrum, or upper lip ; the 

 first pair of jaws or mandibles ; the second pair of jaws 

 or maxillae, which are provided with a pair of palpi, 

 or feelers ; and the lower lip, or labium, also bearing 

 a pair of palpi. 



