THE HEAD. H 



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

 following the same authority, the large workers of 

 Camponotus ligniperdics 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 fidiginosus, 200; in Tapinoma erra- 

 ticum, 100 ; in Plagiolepia pygvicea, 70 to 80 ; in 

 Lasius fiavus, about 80 ; in Bothriomyrmex merv- 

 dionalis,55i in Strongylognaihus iestaceus,Stenmnina 

 Westivoodii, and Tetramorin^m ccespituTn, about 45 ; 

 in Pheidole 'pallidula, about 30 ; Myrmecinci La- 

 treillei, 1 5 ; Solenopsis fugax, 6 to 9 ; while in Ponera 

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

 and in Typhlopone the eyes are altogether wanting. 



The number of facets seems to increase rather with 

 he size of the species than with the power of vision. 



The ocelli are never more than three iu 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 parte are the labrum, or uj^per lip ; the 

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

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

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

 a pair of palpi 



