196 



THE BRITISH NATURALIST. [October 



lowland valleys long ages before the swarm of European immigrants, 

 which followed in the wake of the lengthening summers, arrived to 

 dispossess the aborigines, driving them up the hills or out of existence 

 altogether. There are many such species faithful still to the secular 

 traditions of their race. We sometimes speak lightly of the mutability 

 of specific form, but instances like these impress us more with its 

 persistence. Here we have a case where a period of perhaps more 

 than a thousand centuries has failed to modify even the mere correla- 

 tion "which exists between the species and its environment, in this 

 instance, of heather and quasi glacial conditions ; and one would 

 certainly imagine that racial habit would be less fundamental and 

 more susceptible of modification than structure. Probably the former 

 change would involve the latter, but in any case we have no reason 

 to suppose that this Miscodeva avctica we have just picked up from 

 under a loose stone differs in the slightest degree from his ancestor 

 who enjoyed his little span of life when the great glaciers of the 

 Welsh hills shrank backwards up the valleys during the short 

 summers of that rigorous age. Such considerations many indeed 

 correct hasty assumptions as to the probable rate of evolution o 

 species, and suggest some dim idea of the vast time required for the 

 modification of even the simplest specific characteristics. Another 

 insect we find also up here, to which the same remarks apply, 

 Pterostichus vitveus. This species has a brassy look unlike most of the 

 other Ptevostichi besides being easily identifiable by the deep punctures 

 on the elytra ; — of this beetle we take quite a series. The commonest 

 Brachelytra under these stones are Othius fulvipenne and Xantholinus 

 punctulatus but we also take several specimens of Conums pubescens. 

 There are two Bvadycelli, B. cognatus and B. similis — both very plentiful. 

 For the mountain species Nebria Gyllenhali we search in vain. That 

 appears not to be in any special degree a heather lover although 

 generally taken at a high altitude, Carabus catenulatus of course occurs 

 commonly, and of the other common Geodephaga met with up here 

 there are Clivina fossor, Leistus ferrugineus, Anchomenus pammpunctatus, 

 and four common Ptetvostichi. 



Thus filling our bottles, like the net of the parable, with fish good 

 and bad, we gradually approach the summit. Near the top, even 

 after the long period of dry weather which we have been enjoying, the 

 ground is boggy and there are deep peaty holes full of water. Trying 

 some of these with the water net we find the principal result to be a 

 mass of black and malodorous mud, one beetle only permits itself to be 

 seen — and captured — an Agabus evidently, and on a hasty inspection 

 we put it down as only Sturmii, one of the commonest of that genus. 

 This beetle, however, was not Sturmii, careful examination at home 

 revealed it to be Agabus congenor, a much rarer insect. This was one 



