198 



THE ENTOMOLOGIST S RECOKD. 



follow in writing, is so artificial that it cannot come anywhere near 

 showing the actual relationships. The more one studies variation, the 

 more one sees that it always works oat into what can best be pictured 

 materially by the spherical shape. In limited groups, such as the 

 Gri//iocera and Wiopalocera afford, we also must conclude that all the 

 minor groups now in existence are terminal and collateral lines on very 

 nearly the same plane of the sphere, and that we rarely meet with 

 any which carry us back to slightly deeper planes ; still this is always 

 comparative, and should only be borne in mind as a warning against 

 childish attempts to construct fantastic phylogenetic trees of descent. 

 Even in the groups which seem comparatively the lowest and most 

 ancient by many characters, one always runs up against some charac- 

 ter clearly showing close analogy to the apparently highest and most 

 distinct groups, and vice versa. It would seem that characters develop 

 entirely independently of each other. Let me simply mention the 

 Orypocera-Wke cocoon of the Parnaasins. In practice, we can only set 

 to work by describing first those forms of each group which by the 

 average of their characters give one the impression of being the 

 simplest and lowest, and gradually passing to the highest ; then we 

 must take up the next group and deal with it in the same way. This 

 method, of course, has the inconvenience of bringing together the 

 highest forms of one group and the lowest of the next, so that one 

 jumps back abruptly from the former to the latter, while the lowest 

 forms of the two groups, may really come much nearer each other 

 than the order followed shows, but, notwithstanding, it is always a 

 better plan than the confusion which would ensue if, tempted by some 

 striking resemblance, one broke the rule, in some cases, and one 

 inverted the order, as has been done by some authors. 



I have readily adopted also the comparatively recent tendency to 

 split up many of the extensive genera of the past into a number of 

 smaller ones, because I fully recognise that they consist in many 

 cases of a lot of species clumsily brought together on the strength of 

 most superficial characters, or even of resemblances, which were only 

 apparent, so that they often comprised species standing further apart 

 from each other than were others placed in different genera. The modern 

 attempts are now aiming at more rational and homogeneous groupings. 

 The arguments brought against it by the numerous entomologists 

 who are only acquainted with Europe, is that very soon there will be 

 a genus for each species, but anybody, who has a knowledge of the 

 fauna of the other parts of the world, is fully aware that each Euro- 

 pean species is, in most cases, the representative of a large group. The 

 very fact that they are found together, or in localities not far distant, 

 within such a comparatively limited area as Europe, is a reason for 

 suspecting they stand far apart from each other, and they may belong 

 to different genera. As a matter of fact one can take it as a general 

 rule that the more similar to one another are the r/eneral areas of distri- 

 tion of two species, the further apart the latter stand to each other specifi- 

 cally. For the same reason the poorer in species of Lepidoptera a reyion 

 is, the further apart those stand from each other. Exceptions are only 

 met with in the cases of very particular surroundings, to which certain 

 genera are especially siiited, for one then finds more species of these 

 genera than would have been anticipated by this rule (such are the 

 Oeneidi or the Coliidi in arctic or alpine localities, or the Sati/ridi in 



