1922 ] 
The Mating of Diacamma 
209 
in this genus and “that there are in each colony one or more fertile 
workers which supply the eggs that delevop into workers and 
males.” And Arnold (1916, p. 195) says of a species of the South 
African genus Ocymyrmex, which belongs to the subfamily 
Myrmicinse: “I have frequently dug up the nests of the variety 
arnoldi [of 0. weitzaeckeri Emery] without ever having found a 
female of any sort, nor have females of any species been des- 
cribed up to now. I believe that the genus will be found to have 
only ergatoid queens, or that the egg-laying function (with the 
production of males and females) is possessed by the whole worker 
caste.” 
The fertile workers of Diacamma which function as queens 
are obviously not to be confused with two other types of wingless 
females, the ergatoid, or ergatomorphic queens and the dichtha- 
diigynes. 1 Ergatoid queens are of rather frequent occurrence, 
either as the only form of fertile female or coexisting in the same 
species with winged queens, in one genus of Pseudomyrminse 
(Viticicola), in at least one genus of Formicinse (Polyergus), in 
several Myrmicine genera (Monomorium, Myrmecina, Lepto- 
thorax, Crematogaster,Harpagoxenus,etc.) and especially among 
the Ponerime (Eusphinctus, Cerapachys, Acanthostichus, Acan- 
thoponera, Paranomopone, Alfaria, Megaponera, Ponera.Ony- 
chomyrmex, Leptogenys, Anochetus and Champsomyrmex). 
In some cases (Leptogenys, Paranomopone, Megaponera and 
Eusphinctus) the queens differ very little from the workers, ex- 
cept in having traces of ocelli, a somewhat thinner petiole or a 
larger abdomen; in others the thorax is more complicated in 
structure and approaches that of the winged queen, while in still 
others (Acanthostichus, Onychomyrmex, Nothosphinctus) there 
is an approach to the dichthadiigyne, which is the only queen in 
all the genera of Dorylinse, a characteristic form with very simple 
thorax, without eyes or with minute vestiges of eyes and ocelli 
and with a huge abdomen. Most of the ergatoid forms may be 
derived from the typical winged queen through a loss of the wings 
and a progressive, degenerative simplification of other characters, 
1A fourth form of female, the pseunogyne, is not discussed because it is pathological and 
does not function as a reproductive caste. 
