146 SIE JOHN LUBBOCK ON THE ANATOMY OF ANTS. 



as they pass forward, it, on the contrary, rises from the anterior surface of the pronotum 

 by several, somewhat diverging heads, and, passing backwards and slightly downwards, 

 is attached to the upper part of the antefurca. It would therefore seem to draw the 

 propectus, and consequently to push the head, forwards. It is obvious that if the head 

 is projected forwards, and the propectus then retracted, so that the head could move 

 freely towards each side, it would be easily turned by the rotators above described. On 

 the contrary, if it be retracted, or if the propectus be thrown forward, so that the 

 posterior process of the head interlocks with the anterior processes of the propectus, 

 the head would be so situated as to retain its position even against a considerable force. 



The next muscles to be mentioned are the elevators of the antepectus; these are 

 two in number. The first (PI. XL figs. 1, 2, 4, 5, and PL XII. fig. 4,/) rises from 

 near the middle of the pronotum, and, passing downwards, is attached to the anterior 

 process of the antepectus. The second is weaker; it is attached to the side of the 

 pronotum, and, passing downwards (PL XL fig. 5,/ 1 ) and slightly inwards, is also 

 attached to the anterior process of the antepectus, close to the preceding. The attach- 

 ment of the first large rotator of the head (e) lies between those of these two muscles, 

 as may be seen in PL XL fig. 5, where f and f l represent the heads of these two 

 muscles, which, when they contract together, would tend to elevate the antepectus. 



The depressor of the antepectus is smaller. It commences (PL XL figs. 5, 6, 7, g) at 

 the lower edge of the pronotum, and, passing upwards, is attached to the upper edge of 

 the antepectus, which therefore, on contracting, it draws downwards. 



Front Legs and their Muscles. 



The legs consist of the following segments : — 1, coxa ; 2, trochanter ; 3, femur ; 4, tibia ; 

 and 5, tarsus, this latter being composed of five segments. 



The description given by Straus-Durckheim of the muscles by which the legs are 

 moved has been adopted by most subsequent writers. According to him, the anterior 

 le°'s have five muscles, four flexors and one extensor. The first flexor rises from the 

 superior lateral and anterior surface of the prothorax, and is attached to the posterior 

 border of the coxa. The second and third flexors rise from the superior and posterior 

 surface of the prothorax, and are attached to the coxa just outside the preceding. The 

 fourth flexor rises from the external portion of the posterior surface of the " rotule," 

 and is attached to the posterior edge of the coxa. Lastly, the extensor rises from the 

 pronotum, near the first flexor, and acts immediately in opposition to the preceding. 



The number of muscles in the Ant appears to be greater than in Melolontha, audi 

 the disposition is in many respects dissimilar. 



The first muscle of the leg (PL XL figs. 4, 7, and PL XII. figs. 1, 4, h) rises from the I 

 anterior lateral wall of the prothorax, and, passing downwards and backwards, is 

 attached to the upper anterior angle of the condyle of the coxa, which, therefore, it 

 would tend to draw forwards and inwards. 



The second (*, PL XL figs. 1, 2, 4 ; PL XII. figs. 1, 3, & 4) lies transversely in the lower 

 and posterior portion of the antepectus. In PL XL figs. 1 & 2 it is seen in section. In 

 PL XL fis?. 4 it is severed close to its attachment. It rises from the central ridge 



o 



