39 



regions of northern latitudes, are found in Madeira on 

 the mountain tops ; each, moreover, possessing characters 

 which are just sufficient (although slight) to distinguish 

 them from their European representatives. 



And if we inquire, on the other hand, into the abo- 

 riginal species of those islands, or, at any rate, into 

 such of them whose naturally acquired range embraces 

 the opposite extremes of atmosphere, we shall detect no 

 less surely (albeit within a narrower space) the result of 

 climatal action on insect form. The Helops confertus, 

 Woll., " varies according to the altitude at which it is 

 found ; being usually deeply striated and rugose on its 

 lower, but subpicescent and much more lightly sculptured 

 on its upper limits. I have taken specimens indeed on 

 Pico Ruivo, and on the mountain-plain of the Fateiras, 

 which are so far diminished in roughness as almost to 

 resemble, at first sight, the H. Pluto*" The Pecte- 

 ropus Maderensis, Woll., which ranges from about 2500 

 feet above the sea to the summits of the loftiest hills, 

 although usually with pale legs, is distinguished by 

 having its femora almost invariably dusky when on 

 its highest elevation ; and, following out the analogy 

 with that beetle, the Trechus alticola, Woll., should 

 perhaps be regarded as an alpine state of the T. custos. 

 The Calathus complanatus, Koll., assumes along the up- 

 land heights a very different aspect to what it does in the 

 regions below, being generally more piceous and convex, 

 altogether broader (in proportion) and shorter, and 

 * Insecta Maderensia, p. 516. 



