46 Mr. T. C. Jerdon on new species of Ants 



of the family of the Heterogynes^ of the section Aculeata of the 

 order Hymenoptera, and divides them as follows : — 



1st. Formica, without sting, the antennae inserted near the 

 forehead, and with triangular jaws ; abdominal pedicle of only 

 one knot or scale. 



2nd. Polyergus, also without a sting, but with the antennae 

 inserted near the mouth, and the jaws narrow, arched or bent ; 

 abdominal pedicle also of one knot. 



3rd. Ponera, neuters and females with a sting; abdominal 

 pedicle of one knot; antennse thicker towards the end; jaws tri- 

 angular; head somewhat triangular. 



4th. Odontomachus, diifers from the last in the one abdominal 

 pedicle ending superiorly in a spine ; antennse very slender and 

 filiform in the neuters ; head oblong, much notched posteriorly ; 

 jaws long, narrow, parallel, three-toothed. 



5th. Myrmica, with sting ; abdominal pedicle with two knots j 

 jaws triangular ; maxillary palpi long. 



6th. Atta, differs from the last only in its short palpi; head of 

 neuters usually very large. 



7th. Cryptocerus, also with a sting; two knots in the abdo- 

 minal pedicle ; head very large and flattened, with a cleft on each 

 side to lodge part of the antennae. (Peculiar to South America.) 



St. Fargeau, in the 1st volume on the Hymenoptera in the 

 ' Suites k Buffon,' divides the Ants thus : — 



1st Tribe. Les Myrmicites, females with a sting; 1st segment 

 of abdomen of two knots. This includes the following genera : 

 1st, Cryptocerus; 2nd, Atta; 3rd, Ocodoma; differing from 

 Atta in its larger head, and the presence of spines. 4th, Myr- 

 mica. 



2nd Tribe. Les Ponerites, females with stiiig ; 1st segment of 

 abdomen of one knot only. It includes the genera Odontomachus 

 and Ponera. 



3rd Tribe. Les Formicites, females without a sting ; 1st seg- 

 ment of the abdomen of one knot only. It contains the genera 

 Polyergus and Formica. 



It will be shortly seen that many of our ants cannot be well 

 referred to any of these genera ; but as it is probable that some 

 new genera have been formed by recent writers, I shall in general 

 content myself with referring most of my species to one or other 

 of those here characterized. 



Following the arrangement of St. Fargeau, we have first the 

 tribe of Myrmicites, and the first genus mentioned by him, Cryp- 

 tocerus, being American exclusively, we come to the genus Atta 

 of Latrcille, from which St. Fargeau has separated Ocodoma, the 

 chief distinction being the spines which exist cither on the head 

 or thorax of the latter, which, moreover, is said to have the head 



