a Family of the Hymenoptera Heterogyna. 193 



males and are always larger than that sex. In the Ants however 

 the males are, as far as I correctly know them, invariably smaller 

 and frequently disproportionately so to their partners, consequently 

 this analogy is strongly in favour of the connexion of these genera 

 with the MutillidcB, although three of the preceding speak for their 

 union to the social Ants. I think therefore that this combination 

 and the peculiarity incident to themselves only in the structure of 

 their palpi warrant me in the present state of our knowledge to 

 consider them an osculant tribe intervening between these two, and 

 as such I shall view them. 



With respect to their habits of life I have nothing positive to 

 state ; I will however hazard the hypothesis that they are parasitical.. 

 The Ants and the Staphylini have been supposed to represent each 

 other in the tropical and temperate zones. In the temperate zone, 

 and especially in our own country, the Staphylini are a dominant 

 group, and the ants a secondary one. The reverse is the case 

 within the tropics, and the lines immediately adjacent within a few 

 degrees north and south. In our own country and throughout 

 Europe we find several species of this northern dominant group pa- 

 rasitical in the nests of Ants; and, ceteris paribus,why may there not 

 be, where the Ants themselves are the dominant group, an analogous 

 instance of a genus closely allied to the Ants parasitical upon them ? 

 For the genus Bombus is another dominant northern group which 

 has a parasite — the genus Psithyrus — so like it, that they were not 

 until latterly separated from it, although sufficiently distinct; and in 

 this genus Psithyrus the males greatly predominate in number. 

 Now if I can show that the two genera Dorylus and Labidus are 

 considerably alike, and in many points analogous to the genus Po- 

 nera among the Ants, which although not exclusively a tropical 

 form, yet chiefly so, — which however strays into Europe and as far 

 north as England, but it is most fully developed in Africa and South 

 America, and another form of it wanders into New Holland*, — I think 

 it will be admitted that there is some plausibility in the supposition 

 that these extraordinary genera may possibly be parasites upon the 

 Social Ants ; and when it is further seen that the female, which I sur- 

 mise may belong to the genus Labidus, is both apterous and blind, 

 it becomes further probable that she may seldom quit the nest 

 where she is a parasite ; and this will in a great measure account for 

 specimens of this sex rarely coming to Europe, as it is not to be sup- 



* There are three distinct types in the genus Ponera, which ought to form 

 so many sections, and these seem to follow countries, viz. northern, south- 

 ern and tropical. 



