HYMENOPTERA. 183 



segments of the abdomen with a few scattered erect hairs ; the 

 legs slightly pubescent, the hairs very tine and short ; the head 

 and tirst segment of the abdomen glassy smooth and shining. 

 The head very hirge, more deeply impressed than in cephalotes, 

 more swollen and rounded laterally, and armed behind with two 

 acute spines. The thorax with two long spines anteriorly, two 

 jjosteriorly, and with two minute ones ])laced a little before the 

 middle towards the anterior ])air ; there are also two acute bent 

 spines at the sides just above the anterior coxa;. 



Worker minor. — Of an opake reddish-brown : head large, 

 twice the width of the thorax, deeply notched above ; the vertex 

 transversely quadrate, the anterior angles acute, the posterior 

 ones with a short curved acute sj)ine ; the antenna; slender, and 

 quite as long as the body. The prothorax with two stout acute 

 spines, curved forwards, behind each of which is a minute acute 

 straight s])ine ; a shoi't acute spine on the sides above the anterior 

 coxtc ; the metathorax with two long, acute, nearly upright spines 

 which are slightly curved inwards. The nodes of the abdomen 

 subquadrate, the second about twice the width of the first, both 

 with a sharp carina on their lateral margins, those on the second 

 node terminating in a small tubercle ; the abdomen globose. 



Worker minima. — Very like the worker minor, but is little 

 more than half the size. 



These workers are placed together on the authoritv of Mr. 

 H. W. Bates, who captured them at Santarem ; wliether they 

 can possibly be mere varieties of the common cephalotes. it is 

 impossible to determine without actual observation; the differ- 

 ently formed head, jjcrfectly smooth and naked, as well as the 

 smooth abdomen, appear to characterize a very distinct species. 



.1 Gi^COUOMA SEXDEXTATA. PL X. fig. VJ. B.M. 



Formica sexdens, Linn. Syst. Nat. i. 9f)4. 14 ^ . 



Fabr. Syst. Etit. 395." 23; Ent. Syst. ii. 363. 23. 



IJe Geer, Ins. iii. 608. pi. 31. t. 14. 



Oliv. Encycl. Me'th. vi. 500. 

 Formica sexdentata, Latr. Hist. Nat. Founn. 228. 

 Atta sexdens, Fabr. Syst. Piez. 422. 2. 



Ilab. Cayenne ; Surinam ; Para ; Rio ; South America ; St. 

 Vincent's. 



This is probably the large form of the worker of Q^cndoma 

 ahdominaUs, that which follows being the smaller form of the 

 same species. 



The Rev. Hamlet Clark says of this species : " Twenty years 

 ago it was not known at Rio, except by name, as a pest in the 



