Anatomy of the Male Genital Tube in Goleoptera. 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 JRhizo- 

 phagus depressus the female tube consists of a large basal 

 piece with strong lateral lobes (i. e. 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. Carahoidea. — 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 tlie 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 



