SIE JOHN LUBBOCK ON THE ANATOMY OF ANTS. 151 



directly backwards (PI. XII. fig. 2, z 1 ) and over the preceding to the internal and posterior 

 edge of the posterior leg. 



Although the workers of Ants do not possess wings, Dcwitz has shown * that the larva; 

 possess " imaginal disks," like those from which the wings of the males and females are 

 developed, but smaller. These embryonic wings reach no more advanced stage than that 

 which they have already acquired in the full-grown larva, and in the imago no trace of 

 the front wings appears to be discernible, while it is curious that the hinder wings, though 

 they are smaller in the males and females, are in some cases still indicated by a minute 

 protuberance. 



The presence of wings necessarily entails may other differences, and consequently 



The thorax of the male and female Ants is very unlike thai of the workers — not, indeed 

 in the arrangement of the muscles already described, bat by the changes and additions 

 contingent upon the presence of wings. The females, as is well known in most cases, 

 strip off their wings soon after the marriage-flight. In Anergates atratulus the males are 

 wingless, and, according to Schenckf, the queens in some cases do not acquire win^s. The 

 great muscles of flight are, as might be expected, very large in the winged Ants ; on the 

 other hand, they are few in number, more simple, as it would appear, tban those of most 

 other insects. There are, indeed, several small muscles attached to the wings ; but the 

 main muscles are only four in number — two elevators and two depressors, which therefore 

 are the same for both the wings. Among most other insects there are said to be an 

 elevator and a depressor for each wing ; in the Lepidoptera, Hemiptera, and certain 

 Hymenoptera (Sawflics) the depressors on each side have coalesced, while in Ants and 

 their allies the same is also the case with the elevators. 



The depressors (PI. XII. fig. 8 & 9, /3) are powerful muscles which occupy a considerable 

 part of the upper portion of the thorax. They rise from the mesonotum and pass hori- 

 zontally backwards, lying close to one another along the median line. At their posterior 

 end they are attached to the two processes of the metaphragma (PL XII. fig. 8) (costal of 

 Chabrier), an arched process concave in front and convex behind, which, startin<T from 

 the true hinder edge of the metathorax, passes downwards, terminating in two processes. 



The elevators (PL XII. fig. 8 & 9, 6) of the wings lie almost at right angles to the pre- 

 ceding. They rise from the meso- and metasternum, and passing upwards and forwards 

 outside the preceding are attached to the wall of the back. 



Immediately under the metanotum in this part of the body lies the so-called " meta- 

 thoracic gland." It consists of a number of large nucleated cells opening into a vestibule 

 'PL XII. fig. 7) by short minute ducts. The inner wall of the vestibule, at least in the 

 workers of Lashis flavus, is thrown into several curved ridges, from which proceed a 

 lumber of strong hairs. The vestibule in this species is elliptic in form and opens to 

 ;he outside by a wide mouth. In other species the shape is different ; in Myrmica 

 "uglnodls it is somewhat S-shaped and the hairs are smaller; in Lasius fuliginosus it 

 alls into two divisions, the outer one funnel-shaped, the inner thrown into a number of 

 spherical chambers. This organ seems to be less highly developed in the males and 

 emales than in the workers. 



* Zeitschr. f. wiss. Zool. 1S7S. f Jahrb. des Yer. fur JSaturkunde im Herz. Nassau, p. 6. 



