The Zoologist — January, 1868. 1047 



these two species, do not perceive the same differences. The "lynx- 

 eyed Haworth" has been unable to observe any of the differences on 

 which Guenee insists, and Guenee, with Haworlh's volume in his hand, 

 declines to avail himself of the teaching of that eminent Englishman. 

 My own bred specimens contumaciously ignore the differences laid 

 down by both Englishman and Frenchman, and cannot be divided by 

 any definitions hitherto printed. I confess myself entirely unable to 

 separate the specimens were they mingled, and I doubt the ability of 

 almost any other entomologist to do so. Nevertheless the larvae of 

 both are thoroughly well known, and differ in food, colour and even 

 in form. 



I could multiply instances to almost any extent, but I feel that there 

 is too much of repetition already, and I have said quite enough to 

 satisfy any truth-seeker. It may possibly be objected that by my 

 calling the moieties of these pairs "species" I remove them from the 

 scope of this paper, — namely, variation, — but this difficulty is very 

 trivial : so that the subject is thoroughly ventilated, it matters little 

 what terms we employ. Darwinianism would reduce all species to 

 varieties, and all varieties to mere evolutions, so that precision in 

 terms is almost hopeless, but this branch of the inquiry is open to 

 future investigation. 



The substance of this paper was read before the Entomological 

 Society on the 2nd of February, J 857, and elicited the following 

 observations, as reported by Mr. Shepherd, the Secretary (see Zool. 

 5525) :— 



" Mr. Stainton observed that the theory of pairs would be completely 

 upset if the list were extended to European Lepidoptera, as there 

 would be found in many instances continental species quite as closely 

 allied to the pairs mentioned as these British species are to each olher. 



" Mr. Westwood said that he had heard, for the first time, a theory 

 proposed capable, as was asserted, of being tested by the productions 

 of a limited geographical range like Great Britain. He had supposed 

 it to be generally admitted that a knowledge both of existing and 

 extinct forms was requisite for the proposition of natural laws. Was 

 it intended that in each country throughout the world these double 

 species should occur? Was it only iu Lepidoptera they were to be 

 looked for ? Was it intended that each species should be thus 

 divided, as it were, into two subspecies ? Moreover, in the instances 

 cited, it was evident Mr. Newman had adduced relations of analogy, 



