68 Le Conte on the Pselaphide of the United States. 
It will be seen that notwithstanding the difference in the 
structure of the palpi, I have placed Ceophyllus as the Amer- 
ican analogue of Chennium. The form of the body, and in 
fact the external characters are exactly similar in the two 
genera. And on account of the variation above-mentioned, 
of the cephalic organs, and especially of the palpi, (as noticed 
in Tychus and Ctenistes,) it is obvious that a similarity of 
structure in these organs is not necessary to a strong affinity 
between two species; and I have in this instance considered 
it of secondary importance, as compared with the general 
habit, and the very peculiar structure of the antenne. 
It will be observed too, in comparing a number of species 
of any genus of Pselaphidz, that however much the relative 
proportions of the joints of the antennze vary, there is still a 
particular appearance, depending perhaps on the method of 
articulation, which enables a practised eye at once to recog- 
nize the antennz of each genus. On this account I have 
been led to consider in this group the structure of the antenn® 
as of fundamental importance in arriving at a philosophical 
arrangement of the genera in their mutual relations. 
The differences already alluded to are, however, so slight 
as scarcely to be appreciated in a description. Not so with 
the manner of insertion of these organs; here we find great 
and important variations: many having the antenne inserted 
under the front, as in many Brachelytra ; while others have 
the front porrected and elevated into a narrow tubercle, upon 
or under which the antennz are inserted. 
Using this principle of division, the genera fall into two 
very natural series; which to some extent repeat each other.’ 
! Another reason why I consider the position of the -— as of primary im- 
portance in the division of this group, rather than the number of the articulations 
the 
tarsal , Which are the bases of Aubé's tables, is that 
the character selected by me is entirely independent of particular stages of develop- 
fter the light which en thrown al researches, on 
trae signification of allied animals, scarcely any naturalist will he inclined to deny 
the existence of series in nature, which sta 
can be traced in different directions to very diverse forms. ' Tie partici 
iiimbers vet each series therefore stand in — relation to sh ey m nu 
