48 bulletin: museum of comparative zoology. 



gaster is greatly expanded to accommodate the voluminous ovaries. 

 On closer examination it is found that in each of the four genera men- 

 tioned the female differs from the congeneric worker in certain peculiar 

 characters. This will best be seen by a comparison of the worker and 

 female Lobopelta with the corresponding phases of OnychomjTmex. 

 Many years ago I called attention to the fact that the female Lobo- 

 "pelia elongata Buckley of Texas has no winged female, but that each 

 colony contains a single egg-producing individual, which agrees in 

 all respects with the worker, except in the larger size of the abdomen 

 and the somewhat more compressed petiolar scale. While at Kuranda 

 I succeeded in finding two females of another species (Leptogenys 

 (Lobopelta) fallax Mayr subsp. fortis Forel), a small-eyed form which 

 lives, like the species of Onychomyrmex, in red rotten logs in the 

 primeval rain-forest. One of these females was the mother of a 

 flourishing colony of perhaps 300 workers, the other was isolated in a 

 small cavity in a large log and was, therefore, about to start a colony. 

 I have figured one of the specimens (Plate 2, fig. 8, 9), with the worker 

 (fig. 6, 7) to show the difference between them (in this case greater 

 than those obtaining between the female and worker of Lobopelta 

 elongata) and between the corresponding phases of Onychomyrmex 

 mjobergi and doddi (Plate 1, fig. 3-6; Plate 2, fig. 3-5). It will be 

 seen that in the Lobopelta female the petiole is very much more 

 compressed and more curved forward than in the worker, the thorax 

 more convex and furnished with a small scutellar sclerite and that the 

 head is more orbicular and less rectangular and has distinctly larger 

 eyes and a single ocellus. In the female Onychomyrmex the eyes are 

 not larger than in the worker, there are no traces of ocelli, the head is 

 dilated anteriorly, with rather straight, posteriorly converging sides, 

 and with very different mandibles, while the petiole exhibits a peculiar 

 modification as compared with that of Lobopelta, being greatly 

 swollen behind and much contracted in front. The female Acantho- 

 stichus differs from the worker, according to Emery, in its rounded 

 head, larger eyes, the presence of three ocellar pits, more widely 

 separated frontal carinae, broader thorax, much larger abdomen, the 

 absence of prickles on the sides of the pygidium, and a different 

 pubescence on the abdomen. The only external differences between 

 the female and worker Paranomopone are the presence of a median 

 ocellus in the former and a larger postpetiole and gaster. These 

 comparisons all point to the conclusion that in each of the four genera 

 ergatomorphic females have been developed independently by simpli- 

 fication, or atrophy from the primitively winged type of female during 



