THE TEMPORARY SOCIAL PARASITES. 



449 



sis, dalyi, abcrrans, ranavolonce, agnctis, daisyi, inartluc and dcprcssa) 

 from Madagascar, India and the Malayan region, because they have 

 unusually small, glabrous females, with falcate, pointed or very oblique 

 mandibles, abbreviated frontal carinae and sometimes very strong 

 epinotal spines and a robust abdominal pedicel. The workers of these 

 various forms are much like those of the ordinary species of Crcinus- 

 togaster with large queens. In one species of Oxygync ( ranavalonce, 

 Fig. 265), according to Emery (18970), the aged female has the gaster 

 enormously enlarged and subspherical like that of the mother queens 

 of the permanently parasitic Ancrgatcs (Fig. 279, b). Forel has sug- 

 gested that the structural peculiarities of the O.vygyne queens are prob- 

 ably correlated with peculiarities of habit. Comparison of a series of 

 these insects, kindly given me by the eminent myrrnecologist, with the 

 microgynes of Formica and 

 Aphamogaster, convinces 

 me that they must be temp- 

 orary parasites on other 

 species of Cremastogaster. 

 Their sickle-shaped mandi- 

 bles, so much like those of 

 Polycrgits and Strongylo- 

 (jnatlnis (Figs. 271, 273) 

 point to a method of assas- 

 sinating the host queen 

 similar to that employed by 

 Bothriomyr.mex. The sug- 

 gestion here advanced 

 would, at any rate, consti- 

 tute a good working hy- 

 pothesis in carrying on 

 further researches on the 

 species of Oxygyne. 



While studying the foregoing known and hypothetical cases of tem- 

 porary parasitism, one's attention is arrested by the following consid- 

 erations of general interest : 



1. Temporary social parasitism occurs in several unrelated species 

 belonging to three of the five subfamilies of Formicidae, and must 

 therefore have originated independently on more than one occasion in 

 the past history of the family. 



2. Parasite and host are always members of the same genus or of 

 closely allied genera. This seems to be necessary, because such inti- 



30 



FIG. 265. Female of O.vygyne ranavaloncc. 

 (Emery.) a. Virgin female, showing falcate 

 mandibles : b, fertile female with enlarged ova- 

 ries and gaster. 



