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. iveifzaeckeri 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. 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 Pseudomyrminae 

 (Viticicola), in at least one genus of Formicinse (Polyergus), in 

 several Myrmicine genera (Monomorium, Myrmecina, Lepto- 

 thorax, Crematogaster,Harpagoxenus,etc.) and especially among 

 the Ponerina3 (Eusphinctus, Cerapachys, Acanthostichus, Acan- 

 thoponera, Paranomopone, Alfaria, Megaponera, Ponera.On^'- 

 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 Dorvlinge, a characteristic form with ver^^ 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, 



lA fourth form of female, the pseunogyne, is not discussed because it is pathological and 

 does not function as a reproductive caste. 



