THE NATURALIST. 



VOL. III., NO. XXII.— JULY, 1838, 



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SOME REMARKS ON SPECIFIC DISTINCTIONS. 



By Peter Rylands, Esq. 



At p. 20 of the second volume of The Naturalist, noticing the difficulty of 

 testing the validity of certain presumed species of insects, I remarked that " should 

 there be found specimens which vary in such a manner as to form a connecting 

 link between the supposed species and the established one, the true value of the 

 former is at once understood" — believing that, in such a case, it ought to be 

 considered a mere variety. Mr. Blyth, doubting the correctness of this opinion, 

 favoured the readers of The Naturalist (Vol. II., pp. 288, &c.) with some obser- 

 vations on the subject, the general tenor of which was sufficiently gratifying to 

 me to induce a feeling of indifference to, if not forgetfulness of, the cause which 

 led to their publication. After this long interval the subject would not have 

 been recurred to on my part, did I not believe that good must result from a 

 calm and candid discussion of the question at issue, and that it well merits further 

 consideration. 



Cuvier defined a species to be " the assemblage of individuals, descended one 

 from the other, or from common parents, or from such as resemble them as 

 strongly as they resemble each other ;" and varieties, " the accidental sub- 

 division of species." 



Kirby and Spence remark that " a species is a natural object whose differences 

 from those most nearly related to it had their origin when it came from the hands 

 of its Creator ; while those that characterize a variety have been produced since 

 that event." 



Notwithstanding these strict definitions, naturalists have long been puzzled to 

 discover some certain diagnostic whereby a variety may be distinguished from a 

 species. The authors last quoted (Introduction to Entomology, Vol. IV., p. 397) 

 state that, " in general, where there is no difference in form, appendages, and 

 organs, proportions, sculpture, and larvae; — colour alone, especially in insects 

 inhabiting the same district, only indicates a casual variety." Dr. Burmeister re- 

 marks [Handbuch der Ent., p. 588) that " one important character which especially 

 identifies the sub-species [ov variety] with the species is, that they are fertile 

 VOL. III. — NO. xxii. 2 z 



