194 



WILLIAM MORTON WHEELER. 



leaping in Anochctus is precisely similar, as shown by the observa- 

 tions of \Yroughton ('92) on A. scdillotii var. indicus of India, 

 and of Biro (Emery, '97) on a Papuan species. Among the Dace- 

 tonini it has been observed by Hetschko in the Brazilian Stni- 

 migcnys salicns (Mayr, '93) and by Biro ('97) in S. chyzcn 

 Emery ('97) of New Guinea. The worker of the latter species 

 is able to leap backward to a distance of 20-25 cm., or about 100 

 to 150 times the length of its body, but this behavior is not ex- 

 hibited by the female. Forel ('93) believed that the Neotropical 

 Acanthognathiis occllatus Mayr and Daccton annigerum Latr. 

 might be able to leap in the same manner. I have failed to observe 

 the habit in the allied Australian ants of the genus Orectognathus. 

 All the retrosalient ants, however, leap rather reluctantly and only 

 under certain conditions, and the length of their leaps varies 

 directly as the degree of solidity of the objects against which they 

 happen to close their mandibles. 



Prosalience is exhibited by at least three very different groups 

 of ants : certain bull-dog ants of the Australian genus Myrmecia, 

 Gigantiops, and the extraordinary genus Harpegnaihos, or Dre- 

 panognathus, as it was formerly designated, of the Indomalayan 

 Region. 



The leaping Myrmecias, popularly known as " jumpers " in 

 Australia, comprise the members of Emery's subgenus Pristo- 

 mynnccia (fuh'ipcs Rog., mandibularis Sm., and piliventris Sm.) 

 and the smaller species of Myrmecia sens. str. allied to nigrocincta 

 Sm. and pilosula Sm. I have frequently seen these ants jump 

 distances varying from one to a few inches. When disturbed M. 

 nigrocincta and pilosula, especially, present a ludicrous appearance 

 as they bound out of their small mound nests in a series of short 

 hops like Lilliputian cavalry galloping to battle. Examination of 

 these ants reveals a structural peculiarity which has been over- 

 looked by previous observers, namely, a distinct elongation and 

 basal incrassation of their hind femora, as compared with the hind 

 femora of the other nonsalient species of the genus. In Fig. 2 

 the hind femur of a worker M. nigrocincta (c) and that of a small 

 worker of M. sanguinca of the same size (d) are drawn to the 

 same scale. The greater length and volume of the femur of the 

 former species shows a distinct approach to the conditions in the 



