i?i the Tetramerous and Trimerons Coleoptera. 67 



since the number of joints in the tarsi of Coleoptera does not 

 vary so much as has been supposed. This, it is |;rue, is not an 

 objection that will much affect the series of the Genera In- 

 sectorum, so far as that work may relate to affinities, because it 

 matters little whether insects are to be held together by being 

 all pentamerous or all tetramerous ; but it most seriously atiects 

 the nomenclature of the tarsal system, — since, if I place a natural 

 group with five joints to each of the tarsi among Tetramera, and 

 another with four joints among the Trimera, I clearly give them 

 a false description as well as an erroneous name. 



It requires little observation to perceive that Aristotle's group 

 of Ptilota is typically pentamerous, or, in other words, that it 

 has in its most normal forms five joints to the tarsus. Aberrant 

 exceptions there are, however, to all rules of this kind ; and, as 

 we have seen above, the arrangement of Coleoptera given by the 

 French school of naturalists is grounded on such exceptions. 

 Observations universally adopted as accurate, and judged of suf- 

 ficient importance to form the basis of a system, are not likely 

 to be viewed with suspicion by young naturalists. While, 

 therefore, on entering upon the science, I perceived that the 

 tarsal system was at utter variance with natural affinities, I 

 made no doubt of the statements upon which it was founded 

 being in the main correct. It was certainly evident, as shown 

 above, that this system, as propounded by the French entomolo- 

 gists, would not contain all Coleoptera ; and, on the other hand, 

 that Illiger and Reichenbach had even exploded the section of 

 Dimera ; but no one carried his scepticism so far as to express 

 doubts of a Linnean Ceramhijx and Curculio being different from 

 a Carabus in being tetramerous, or of a Coccinella being properly 

 separated from a Cln-i/somela in being trimerous. The study of 

 natural afiinities, however, is of that admirable nature, that, 

 while founded on observation, like a well-proportioned build- 



K 2 ing 



