Turning now to the _Labidus_ question: many American species of this genus have long been known, though all of them {177}by the male sex only. The discoveries (to be subsequently alluded to) made in the Old World as to the relations between the driver ants and _Dorylus_ raised a suspicion that _Labidus_ might be the male of _Eciton_, the distinctions in the two cases being very analogous: this conjecture has been almost proved to be correct by the recent observations of Hetschko and W. Müller. The latter, who observed the temporary nests of _Eciton hamatum_, confirms Belt's statements as to the ants hanging together in clumps, like swarms of bees; he also states that the change from one temporary abode to another takes place at night, though, as is well known, the hunting forays of this ant are carried on in the daytime. The periods of migration appear to be determined by the time at which all the larvae have assumed the pupal state, this at any rate being the time chosen in the case observed by Müller. This naturalist bagged a part of one of the nests by the aid of ether, and found the larger portion to consist of pupae; there were also some larvae and eggs; a specimen of _Labidus_ (_L. burchelli_) was also found on friendly terms with the _Eciton_-workers; and myrmecophilous Coleoptera were discovered. The pupae are enclosed in cocoons. Persistent search failed to reveal any female, but the examination was made under great difficulties. Müller also states that the earliest pupated larvae yield soldiers, the latest the smallest forms of workers. From observations made by Forel on a pupa, it seems probable that a wingless form of male may be found to exist. If therefore, as appears practically certain, _Labidus_ is the winged male of _Eciton_, it is probable also that males of more or less worker-like form exist, as is now known to be the case in some other Formicidae. We may here notice a peculiar apterous female ant recently described by André under the name of _Pseudodicthadia incerta_. He thought this might prove to be the female of _Eciton-Labidus_; but his description and figure are imperfect, and do not greatly support his idea of a connection between _Eciton_ and _Pseudodicthadia_.