632 Mr. D. Sharp and Mr. F, Muir on the Comparative 
(3) the ontogeny. ‘To which may fall to be added as a 
fourth, the structure of the sexual glands. 
We had at first decided not to write a phylogenetic 
section for our memoir, as our knowledge is so imperfect 
and is liable to correction in so many ways. Yet recalling 
the fact that the other departments are also but im- 
perfectly known, so that there is but little agreement 
amongst phylogenists, we have concluded that a section 
on phylogeny of the genital tube, though somewhat pre- 
mature, may be welcome nevertheless. It will at any 
rate exhibit the difficulties and complexity of the 
subject. 
Our inquiry has led us to suggest the arrangement of 
Coleoptera in eight series. Remarks on these series 
appear in the section taxonomy. A connected account of 
their apparent relations, and an account of some of our 
reasons for the conclusions we have come to follow this, 
and the most important points will be found discussed 
under Phytophagoidea and Byrrhoidea. 
1. Lyrrhodea.—The aedeagus appears to us to be in 
this series in its simplest condition, and at the same time 
to be the form most capable of modification to result in 
the structures we meet with in other groups, as we have 
already mentioned. ‘The series itself is, however, far from 
being homogeneous and we shall not be surprised if some 
of its forms prove to be really separate series. Cupes and 
Omma may be mentioned. Also Gyrinidae. Atractocerus 
requires serious attention, and it may be doubted whether 
Buprestidae are really in phylogenetic accord with other 
Byrrhoidea, 
We have frequently stated that we consider the trilobe 
form of aedeagus as it 1s exhibited by the Byrrhoidea to 
be the simplest, and probably the more primitive, of the 
existing forms. Our reasons for this are (1) that “low” 
forms of various divisions are found to possess the genital 
tube in a state but little different from the trilobe of the 
Byrrhoidea. (2) That in highly specialised groups of 
which there exist a sufficient variety of forms we have 
always been able to find in certain cases one or more 
points that form an apparent transition to the trilobe. 
This of course may be illusory (as indeed we shall argue 
when discussing under Phytophagoidea the questions 
connected with “lateral lobes”), but it shows that the 
modification of the trilobe is to the imagination easy, and 
