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. Byrrhoidea. — 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. Atractocerns 

 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 is 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 speciahsed 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 



