Anatomy of the Male Genital Tube in Coleoptera. 633 
we all know that in the absence of direct evidence phylo- 
genists have only too frequently to resort to the use of 
the imagination. (3) The internal sac is found in its 
simplest condition among the trilobe forms, and attains 
its highest development amongst forms in which the 
aedeagus is very different from the simple trilobe. (4) In 
various females that we have examined the structures 
depart but little from the trilobe form. Thus in Rhizo- 
phagus depressus the female tube consists of a large basal 
piece with strong lateral lobes (7.¢. there is a tegmen of 
the trilobe form). The median lobe is rather small, and 
its chitinisations are less compacted and coadapted than 
in the male aedeagus, the duct opens at the apex, and 
there are basal struts. In this species the male (fig, 101) 
departs considerably from the trilobe form. 
2. Caraboidea.—This division, as limited by us, is re- 
markably homogeneous, and forms as regards the aedeagus 
one of the most satisfactory series of the Order. We have 
suggested that it might possibly be derived from Byr- 
rhoidea. This would be accomplished by dragging the 
lateral lobes away from one aspect of the median lobe, 
and connecting them with a condyle on the other aspect. 
The basal-piece must become membranous (it is imper- 
fectly chitinised in Cicindelidae), and completely ride over, 
or cloak the base of the median lobe. The last character 
being of a Cucujoid nature. We have no belief in such 
changes having occurred during the Coleopterous stage 
of the phylogeny. 
3. Cucujoidea.—This is an assembly of many families, 
and will probably require much emendation and even 
division. The main points of distinction from Byrrhoidea 
are that the tegmen rides over the median lobe, and that 
the lateral lobes are differently placed. The question of 
deriving the series from Byrrhoid ancestors is discussed in 
our considerations as to series 8, Phytophagoidea. 
4, Staphylinoidea.—In the higher forms this is a most 
distinct division, the aedeagus appearing to function by 
means of an aneurism of its basal part. We have asso- 
ciated Silphidae with Staphylinoidea because in the lower 
forms of the great family Staphylinidae (Omaliini and 
Piestini) the peculiar structure is much less perfect, so 
that we think it possible the Silphoid forms and the 
Staphylinoid forms may prove to be not separable by the 
male genital tube. The lateral lobes are extremely varied 
