Mr. H. T. Stainton on Genera. 115 



of these single species represents the type of one extensive genus, 

 but of which the other species are unknown to us, not occurring 

 in the restricted area to which our investigations have been 

 confined. 



That the limits of genera are not always closely defined, that 

 they shade off as it were imperceptibly at the edges, is nothing 

 more than we might have anticipated. Rigidly defined mathema- 

 tical genera, with no intermediate species, exist only as phantoms 

 in the brain of the systematizer, and, brought face to face with 

 the facts of nature, such phantoms vanish. 



I do not profess to have propounded anything novel in the 

 preceding observations, and I believe it will be found that what I 

 have said is so exactly similar to the remarks on the same subject 

 by Mr. VVoUaston in his Treatise " On the Variation of Species," 

 that on that very account it may appear still less necessary to 

 intrude the subject upon the Society. My object, however, has 

 been to bring the subject primarily before the notice of some of 

 the readers of the Society's Transactions, and with this view I 

 have purposely been as brief and as explicit as I could. 



XIII. Observations on the Difficulties attending the Dis- 

 crimination of the Species of the Genus Stylops. By 

 Frederick Smith, Esq. 



[Read May 5th, 1856.] 



The morning of the 16th of April, 1856, held out a promise of a 

 good day for collecting bees, and so it proved, as my son on that 

 day obtained not less than fifty specimens of Andrenidce, on Hamp- 

 stead Heath, in the finest possible condition, together with some 

 examples of Nomada signata, N. horeal'is and JV". Lathburiana. His 

 magazine was a bottle containing bruised laurel, for miscellaneous 

 collecting, but for any specimens of particular interest, I fur- 

 nished him with pill boxes, of the latter kind he obtained the 

 sexes of Andrena fulva, taken " in coitu," and a pair of Andrena 



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