﻿^ THE ENTOMOLOGIST. 



genera, by the energies of various "name-mills" — energies 

 that have led to a large amount of cross classification, for we 

 have included within the same aberration parallel forms of 

 several microgenes. Details regarding the various forms are in 

 tabular form at the end of the paper. 



Let me return, for the sake of illustration, to the plant 

 genera enumerated above, the microgenes of their several 

 species having been so systematically worked out by Babington, 

 Baker, Jordan, Sudre, Dumortier, and other equally well-known 

 botanists. Possibly not one half of the named forms described 

 in these genera have the slighest claim to be regarded as 

 " species," but are hybrids between the various microgenes, 

 as has been experimentally proved in certain cases. These 

 hybrids, naturally, are in many instances intermediate to two 

 well-defined microgenes, and transition forms crop up and 

 provide the causes of so much apparent variation within the 

 limits of the Linnean species. Such spurious transition forms 

 give then, in the absence of Mendelian dominancy^^ what appear 

 to be cases of continuous variation ; when viewed correctly they 

 prove the opposite. 



In spite of this continual hybridising with allied forms the 

 microgenes are not swamped, and continue true to type, proving 

 that they are, at least, of greater value than the hosts of named 

 ** aberrations." The form which, for the sake of convenience, 

 I have labelled 0. pinivoi-aria surrounds here a colony of 

 O. autiimnata vera (or, to use the trinominal nomenclature now 

 so popular, 0. autumnata atitumnata), and is overlapped by 

 0. filigrammaria. Nevertheless, the three forms, year after 

 year, remain quite distinct ; so too do 0. alticolaria and 

 O. filigrammaria, which also overlap. 



Turning now to the Linnean species, it becomes necessary to 

 give my definition of what is included in the term. In my own 

 mind I define a Linnean species as a form which, hybridised 

 with a form of equal value, yields progeny which, when paired 

 inter se or crossed with either parent, is more or less sterile ; in 

 some cases the first cross is sterile. In addition, in the Insecta, 

 I attach great importance to the genitalia. 



That Oporabia autumnata and 0. dilutata are Linnean species 

 my experiments confirm, but the proofs obtained from other 

 considerations have been ably worked out by Prout (Ent. 

 March, 1900 ; Trans. City of London Ent. and Nat. Hist. Soc. 

 1899). It is not necessary, therefore, to repeat what he says 

 here. The phylogeny of the two species is very clear, and may 

 be readily worked out in several ways. 0. autumnata * is Hol- 

 arctic, whilst 0. dilutata* is practically confined to the Pal^earctic 



■'• lu this paragraph it will be understood that the names "dilutata" 

 and " autumnata " are used in the Linnean (collective) sense, and also at 

 other points where no confusion is likely to arise. 



