33 



contour of the insect tribes. Thus, to go no further 

 than Ireland, we find that the specimens of Silpha 

 atrata, Linn., so abundant throughout England and the 

 whole of Europe, have put on (it may be from the moist- 

 ure of the atmosphere, or from some other obscure 

 influence) the appearance of a distinct race, so distinct 

 indeed as to have long received another name, S. subro- 

 tundata, from British naturalists. I think it far from 

 improbable that the Tachyporus nitidicollis, Steph., an 

 insect eminently characteristic of that country (and one 

 on which I have lately offered some remarks *), is but a 

 darker climatal modification of the common T. obtusus : 

 and it is well known that the examples of Pelophila 

 borealis, Payk., from Killarney and Loch Neagh are per- 

 manently larger, and much more metallic, than those 

 from the Orkneys. The Nebria complanata, Linn., 

 assumes a more pallid hue in the neighbourhood of 

 Bordeaux than it does on the sandy coasts of Devonshire 

 and Wales : and I have but little doubt that the Omu- 

 seus nigerrimuSj Dej., of Spain, the north of Africa, and 

 Madeira, is a geographical state of the 0. aterrimus of 

 Central Europe. The Sitona gressoria, Illig., so univer- 

 sal throughout the Mediterranean districts, Madeira and 

 the Canaries, may be but the subaustral form of S. grisea. 

 The Bembidium obtusum, Sturm, is shorter and less 

 parallel in our own latitude than it is in the Madeiraii 

 group and along the Mediterranean shores : whilst the 

 Holoparamecus niger, Aube, of Madeira and Sardinia is 



* Zoologist, xiii. p. 4655. 



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