78 ENTOMOLOGICAL NEWS. [March, 



riod had arrived, only a long series of specimens could be truly 

 typical of the species. The next step in this evolution would be 

 the arrival of a form which began to occur in relatively large 

 numbers, and when the time arrived when this new form was 

 represented in reasonable proportion, to the greater number of 

 individuals which still resembled the original type, we would have 

 what I would consider a good variety. This variety would be 

 connected with the ground type by intergrades, but the differ- 

 ence between it and the intergrading forms would be, that it would 

 be more constant than any other selected individual, and reason- 

 ably constant as compared with the original type. Evolution 

 might go further, or it might not. If it went on we would get 

 other varieties, with intergrading forms between each. The spe- 

 cies would be represented, let us say, by a ground form, the type, 

 and suppose we stop at three varieties with intergrades between. 

 Normally, the varieties would be more fixed and more numerous 

 as they more closely resembled the type. But any variety would 

 be less rare than the intergrades. On the other hand if evolution 

 stopped with one variety, the next step would be the gradual 

 disappearance of the intergrading forms, which of course would 

 also occur in time regardless of the number of varieties thrown 

 off. The first individual appearance of one of these extreme 

 forms being at the moment the most distant from the type, but 

 the forerunner of others similar to it, and thus the precursor of 

 a variety, is what I understand by Aberration. 



With this idea of the meaning of intergrades we find that 

 Intergrades are of three classes. 



First, the fixed species has become variable, and all the indi- 

 viduals differ essentially from all others. Possibly there may be 

 a rare and extreme form, the "aberration." 



Second, there may exist one or more distinct forms called va- 

 rieties, with intergrading forms between the varieties, and be- 

 tween the type and the variety most similar to it. But given a 

 thousand insects it should be possible to separate the varieties 

 into groups; when it would be seen that in a given lot, under a 

 given name, the individuals would resemble one another as much 

 as the typical specimens would in similar numbers. The inter- 

 grades, however, would not do this. 



Third, there may exist one or more varieties, each as fixed as 

 the type, but with no intergrades, except where the varieties may 



