42 THE ENTOMOLOGIST’S RECORD. 
of the latter in the nests of Formica rufa and Lasius fuliginosus, that 
some authorities state the number of species to be found with them at 
from 100 to 150. Of these the actual number of guests does not, per- 
haps, exceed a third. 
The principal characters of true guests are found in beetles be- 
longing to the Myrmecophilous Staphylinidae (pl., figs. 1-3), Clavi- 
geridae, Paussidae, Stilphidae, Histeridae, &c., to consist of peculiar 
yellow or reddish-yellow tufts of hair, found on different parts of the ~ 
body. These prove that the beetles possessing them are licked by 
their hosts to obtain the pleasant secretion coming therefrom. The 
presence of a broad short tongue and aborted palpi suggests that those 
possessing these peculiarities are fed directly by the host. These 
adaptive characters, which both point to a genuine hospitable relation- 
ship, are often to be found in the same species. ‘To these may be 
added a peculiar formation of the antenne, which denotes a friendly 
relationship between guest and host, and serves to summon the ant at 
feeding-time by tapping it with these organs. The Clavigeridae (which 
form a sub-family distinct from the Pselaphidae) present an excellent 
example of the combination of these three characters. They are 
genuine guests, differing from the Pselaphidae in their club-shaped 
antenne (consisting of fewer segments), the stunted palpi (organs 
strongly developed in the Pselaphidae), and the shape of the Ist 
abdominal segment, which is very large, hollow at the base, and 
covered with tufts of yellow hair on the concave side. The elub- 
shaped antenne serve as organs of communication and allow of friendly 
intercourse between the beetles and the ants; the formation of the 
mouth allows the beetle to be fed by its host, whilst the peculiar form 
of the 1st abdominal segment and the tufts of yellow hair are closely 
related with the licking of the beetles by the ants. It is, therefore, 
quite correct to look upon these three adaptive characters as the real 
characteristics of the Clavigeridae, and every Claviger must necessarily 
be an ant guest. This is borne out by the fact that, of the 100 dif- 
ferent species of this family already described, by far the greater 
number have been discovered in the society of ants, and of many the 
actual host is known, especially of the European species and those 
from Madagascar and North America. 
We find in certain Termitophilous Staphylinidae two adaptive cha- 
racters, which are a proof of true intercourse, viz.—(1) the broad short 
tongue and short palpi (in the subfamily Aleocharinae, and only 
found in the true guests belonging to the Lomechusa group); (2) a 
swelling of the abdomen, in some cases quite abnormal (Physogastry) 
(pl., fig. 5), and not to be found among Myrmecophilous beetles. 
The mouth-structure leaves no doubt that these beetles are fed directly 
by their hosts, whilst the gigantic enlargement of the guest’s abdomen 
is undoubtedly connected with their mode of life, for it also occurs - 
in the Termitophilous ground beetles, Orthoyonius Shaumi, and by 
their larve, which, when young, are thin and slender, but gradually 
acquire a long bottle-shaped form under the care of the termites. The 
yellow tufts of hair, as in those of the genuine Myrmecophilous beetles, 
are not present in the Termitophilous Staphylinidae with thickened 
abdomen. ‘The tastes of termites evidently differ from those of ants. 
The Termitophilous beetles have not the club-shaped antenne that 
facilitate intercourse between the Myrmecophilous beetles and their 
