36 



In exact conformity with what the above remarks will 

 have prepared us for, we find that the Dromius obscuro- 

 guttatus, Dufts., of Central Europe, has undergone on 

 the mountain summits of Madeira changes precisely to 

 that extent which we should have calculated upon ; and 

 although they would seem in reality to be referable to 

 climate and isolation combined, yet, since it is not 

 always possible (as lately stated) to treat the elements 

 of disturbance separately, and it is my object in this 

 short treatise to bring forward a few prominent examples 

 in support of the considerations proposed, rather than to 

 accumulate a mass of material for the registry of which 

 my space would be inadequate, I will quote in extenso 

 the reflections which, during the compilation of the 

 1 Insecta Maderensia/ suggested themselves to me. " The 

 Dromius obscuroguttatus is a common European insect, 

 and the Madeiran specimens recede from the ordinary 

 ones in being slightly larger, and in having their elytra 

 more obscurely striated, with the humeral patch less 

 distinct : their entire surface, moreover, is of a deeper 

 black, a difference which is especially perceptible on the 

 legs. It occurs in the greatest profusion in Madeira 

 proper, though only from about 5000 to 6000 feet above 

 the sea. Although so common throughout Europe, it 

 is perhaps, when geographically considered, one of the 

 most interesting of the Madeiran Coleoptera, as affording 

 a striking example, not only of the modification of form 

 in a normally northern insect when on its southern 

 limit, but as showing likewise how a species, abundant 



