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XL Notes on the occurrence in Britain of some undescrihed 

 Aphides. By G. B. Buckton, F.E.S. 



[Read August 4th, 1886.] 



Plates IV., V., VI., & VII. 



Much interest will always attach to any possible tracing 

 back of a specific form to its natural and more simple 

 groupings, and also to the enquiry what modifications 

 of structure and habit have formerly been the factors in 

 a development from the simple to the complex. For 

 this reason alone, an undue multiplication of described 

 species is to be deplored, for it must tend to complicate 

 a problem which is already sufficiently difficult and 

 obscure. 



In forming a judgment as to the existence of a new 

 species, much must be left to the intuition of the 

 biologist, for, as a sailor may be able correctly to read 

 the sky, and yet be unable satisfactorily to tell you why 

 he comes to an opinion, so it may not be always easy for 

 a man of science positively to state why he decides for 

 or against a form as specific. 



Since the publication of the fourth volume of the 

 * Monograph of British Aphides ' friends have kindly 

 sent to^'me what appear to be several new species, and I 

 venture here to describe certain of them, although they 

 might perhaps better appear in a short supplement to 

 that work. 



Aphis crithmi, Buckton. 



Apterous viviparous female. — Size of body, 0*060 x 0-030 inch. 

 Small, oval, brown, and slightly mealy to the naked eye. Neck- 

 ring, cornicles, and two or more broad irregular patches on each 

 side of the abdomen, dark olive-green or brown. Abdomen pilose 

 and pitted near the carina. Eyes black. Antennae greenish, and 

 about two-fifths the length of the insect. Young individuals are 

 often bright yellow or greenish, with numerous minute spots dotted 

 over the surface. The pupa is of a drab-yellow colour, with black 

 head, eyes, nectaries, knee, and tarsal joints. Wing-coverts yellow, 

 tipped with black or brown. 



TRANS. ENT. SOC. LOND. 1886. PART III. (oCT.) 



