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V. (1) Illustrations of specific characters in the armature and 

 ultimate ventral segments of Andrena ^ . By the 

 Rev. F. D. MoRiCE, M.A., F.E.S. 



[Read February Isl, 1899.] 



Plates V— VII. 



(1) 

 It is generally thought, and has been stated by well- 

 known authors, that the characters of the ^ genital armature 

 and two last ventral segments — so important in many genera 

 — are in Andrena too slight and troublesome to repay in- 

 vestigation. However, during the last few years I have 

 carefully examined them in a large number of specimens, 

 representing all the common Palsearctic species, and as 

 many rarities as I could procure, the number of examples 

 tested in each species naturally depending on the amount 

 of material at my disposal. The result of this investigation 

 leads me to think that the characters in question are neither 

 so valueless, nor so hard to examine, as has been supposed. 

 Those to which I now desire to call attention, though of 

 course lest seen under a compound microscope after com- 

 plete extraction of the parts exhibiting them, can generally 

 be recognised quite sufficiently after a much less elaborate 

 preparation of the specimen, and sometimes after none at 

 all, for specimens often occur in which the genitalia or 

 the ventral apex, or both, are naturally protruded enough 

 to show what is wanted. Nor do they require to be highly 

 magnified ; a " Coddington " is always more than sufficient, 

 and some of them are visible to the naked eye. 



As to their value, they seem to me to have many good 

 points as specific characters. They are often very definite 

 and sometimes quite conspicuous. I have found them on 

 the whole conrstant through long series of specimens. 

 They are equally apparent, whatever the condition of the 

 specimen — however rubbed or damaged it may be ; and 

 though no doubt it is superfluous to spend time over them 

 in the case of species which can easily be determined 

 otherwise, I find that a single glance at them will often 

 enable me to distinguish insects whose other differences 

 would need a prolonged examination ; to recognise abnormal 



TRA-NS. ENT. SOC. LOND. 1899. — PART II. (JUNE) 



