108 



as are those of the B. Atlanticum : and indeed unless 

 viewed in the mass, we should scarcely be inclined to 

 recognize the same species in the many aspects which it 

 puts on between its extremes. The examination, how- 

 ever, of a very large number of examples, and a careful 

 consideration of the several localities and altitudes in 

 which they were taken, has convinced me that there is 

 unquestionably but a single type of form amongst my 

 entire series, since the whole are so intimately connected, 

 by successive gradations both of outline and colour, that 

 it is perfectly impossible to isolate even a single specimen, 

 or to draw a line of specific demarcation between any 

 two consecutive members of the chain. It will be per- 

 ceived, by a reference to the diagnosis, that the insect in 

 question passes imperceptibly from nearly a pure green, 

 through a well-defined spotted state, into one which has 

 the elytra almost testaceous, the paler portions being 

 at last so largely developed as to become confluent, and 

 almost to cover the entire surface. In Madeira proper 

 the darker varieties would seem to be typical ; whereas 

 in Porto Santo the brightly coloured ones preponderate, 

 and in fact are all but universal. Both extremes do 

 nevertheless occur in both islands, the tendency being 

 merely, in either case, to assume the particular modifi- 

 cation characteristic of the spot*. 



And so it is with the outline and sculpture (no less 

 than with bulk and hue) : they also are equally liable to 

 disturbance from physical causes, as indeed has been 



* Insecta Maderensia, p. 78. 



