24 



MR. A. MURE AT ON THE GEO GRAPHICAL RELATIONS OF 



Of 56 members of the European branch of the microtypal 

 stirps, I find 12 which have no greater affinity for one part of 

 the European fauna than another, 3 which are new, but whose 

 general affinity lies with species characteristic of the Mediter- 

 ranean subfauna, 40 whose affinity is nearest to the fauna of 

 the other Atlantic islands, and 1 (PristonycJius complanatus) 

 which is generally distributed in microtypal countries, and which 

 has hence been supposed cosmopolitan, but which in reality has 

 not been found out of the microtypal bounds. Much of the 

 weight to be given to this apportionment of the elements of the 

 isle must depend on the value of my reasons which are given 

 in the notes to the list of species in the Appendix, and to these 

 I must refer the entomological reader. I may only say here 

 that the instances which have had most weight on my own mind, 

 are, 1st, the occurrence of a large Carabus (a hunting carnivo- 

 rous genus limited to microtypal countries, which it would seem 

 impossible to introduce except by continuity of dry land), 

 which, according to the high authority of Prof. Lacordaire, has 

 most affinity with species found in Syria (i. e. in the Mediter- 

 ranean district with which the Atlantic Islands are otherwise 

 most connected); 2nd, but of still more importance, the presence of 

 species of genera which are particularly prominent or abundant in 

 the other islands, as Calosoma, JBembidium, Lceinoplicelus, Anobium, 

 Opatrum, &c. ; and 3rd, and of most importance of all, the pre- 

 sence of new forms allied to species already known as character- 

 istic of or confined to the other islands of the Atlantic, as Mi- 

 croxylobius, JYesiotes, and Notioxenus, representing respectively 

 the prevailing element of Cossonus, Acalles, and Atlantis in them. 

 That a particular genus is represented (however critical this genus 

 may be), when the representation is only by a single species, is 

 not nearly so strong evidence of common origin as common exu- 

 berance of some particular form in both faunas under comparison ; 

 for the occurrence of a single species may be explained away when 

 the presence of many defies dispute. And I rest as much on the 

 occurrence of the typical character of facies as on actual identity of 

 genus or species ; for in the development of new forms Nature 

 often refuses to go by our generic characters, and produces some- 

 thing exactly similar in appearance but with some deviation in 

 what the systematist chooses to call important organs, a deviation 

 which to his mind is fatal to generic identity, but to mine insignifi- 

 cant in the face of persistence of facies. 



