198 WILLIAM MORTON WHEELER. 



In conclusion, two interesting matters of a more speculative 

 nature may be briefly discussed : 



1. The various macrophthalmic, or large-eyed, tropical ants 

 mentioned in this paper, namely, the Formicine genera Gigantiops, 

 Opistliopsis, dLcophylla, Gesomyrme.v, Diinorphomynnc.v, Sant- 

 schi'dla and Myrtnoteras, the Ponerine genera Myrmecia and 

 Harpcgnathos, and I may add also the whole subfamily Pseudo- 

 myrminae, constitute only a small percentage of the more than 

 10,000 extant species, subspecies, and varieties of Formicidse. In 

 the great majority of forms the eyes and ocelli of the female, and 

 especially of the workers, have undergone considerable reduction 

 in size or have entirely disappeared. In the male, however, which 

 is the more conservative sex in ants, the eyes and ocelli are always 

 large. These facts, together with what is now known of the ants 

 of the Baltic amber, suggest that not later than Cretaceous time 

 the females and workers were also all large-eyed, like the Scoliidoid 

 wasps from which the Formicidse are derived, and that they pre- 

 served this condition till after the social habit and a wingless 

 worker caste had been evolved. During the Eocene and owing to 

 the further development of the peculiar nesting and foraging 

 habits, the females and workers became increasingly microphthal- 

 mic and anophthalmic till the small-eyed or blind condition became 



' established in the majority of existing forms. 



2. It will have been noticed that all the known prosalient ants 

 have very large, convex, and minutely faceted eyes, and that all 

 belong to' archaic genera. I have already discussed the antiquity 

 of Gigantiops. The Myrmecias are, I believe, justly regarded as 

 the most primitive of existing ants, survivors, without more than 

 specific diversification, from the early Eocene or the late Creta- 

 ceous. Harpcgnathos includes only a few rare species of very 

 restricted geographical range, evidently relicts on the verge of 

 extinction. It would seem, therefore, that the .leaping habit may 

 have been much more general among the most ancient macroph- 

 thalmic Formicidse, but had been abandoned as incompatible with 

 a more highly developed social organization. This seems to be 

 shown even within the genus Myrmecia, the larger and more domi- 

 nant species of which no longer leap. That this habit should still 

 persist, probably in a degenerate stage, in a few large-eyed forms, 



