OBSERVATIONS ON GIGANTIOPS DESTRUCTOR. 193 



l)e said to have an even more remote origin than the archaic though 

 highly specialized Neotropical vertebrates, such as the opossums, 

 manatees, sloths, armadillos, ant-eaters and tapirs among mammals, 

 or the ostriches and hoatzins among birds. 



The jumping or leaping habits of Gigantiops are so unusual that 

 a more general account of this behavior as it occurs in various 

 Formicidse may not be out of place. There are two very different 

 kinds of leaping ants, one which I shall call '' retrosalient," which 

 always leaps backward, and one that may be called " prosalient," 

 because it always leaps forward. Some authors regard the former 

 as not " leaping," in the proper sense of the term, probably because 

 of the direction and because it is not performed by means of the 

 legs. But such very abrupt displacements of the body are effected 

 in so many different ways in different insects, as, e.g., in Elaterid 

 beetles, Lepismids, Collembolans, cheese-maggots, fruit fly and 

 Vcrnrilco larva, the extraordinary Coleopteran (?) cocoons de- 

 scribed by Berlese ('20, p. 631), etc., that such words as "leaping" 

 can hardly be avoided without pedantry. We even speak of fish 

 or of a cataract " leaping." 



Retrosalience has been repeatedly observed in two quite unre- 

 lated groups of ants, one embracing the Ponerine genera Odonto- 

 maclius and Anochctus. the other the Myrmicine genus Stni- 

 migcnvs. By convergence both of these groups have developed 

 very similar long, straight, and linear mandibles, inserted close 

 together on the front of the head and furnished with large, abruptly 

 incurved teeth at their tips. When excited these ants open their 

 mandibles so widely that they stand out at right angles to the long 

 axis of the head or are even directed slightly backwards. And if 

 one of the insects comes in contact with a solid object in its path, 

 it closes them so suddenly and with such force that they make an 

 audible "click" and the insect is thrown backwards through the 

 air to a distance of several inches. I have described this behavior 

 in detail in O. dams of Texas ('oo). It has also been observed 

 in 0. chdtfcr of Brazil by Schupp (Wasmann, '92) and in the 

 common tropicopolitan 0. hocvnatoda by Nietner ('58), Ferguson 

 (Wroughton, '92), Forel, myself, and others. 1 The method of 



i Borgmeier ('20) has recently described the similar habits of O. affinis in 

 Brazil. " They strike their mandibles against the solid substratum and at 

 the same moment leap 30 to 35 cm. vertically into the air." 



