LINNEAN SOCIETY OF LONDON. Ixix 



Memoirs of the General Helvetic Society (vol. xxiv.), a review of 

 the genus Theohroma, after having compared his specimens with 

 those in the herbaria of Kew, Berlin, and Geneva. 



YI. Italy and the Mediterranean Region. 



The biological interest of the Mediterranean Region, which in- 

 cludes southern Europe, the north coast of Africa, and those lands 

 vaguely termed the Levant, is in many respects the opposite of 

 that of the great Russian empire. Extending from the Straits of 

 Gibraltar to the foot of the Caucasus and Lebanon, over 40 to 45 

 degrees of longitude, by 10 to 12 degrees of latitude, from the 

 southern declivities of the Pyrenees, of the Alps, the Scardus, and 

 the Balkan, to the African shores, it shows, indeed, a certain uni- 

 formity of vegetation through the whole of this length and breadth ; 

 but it has evidently been the scene of great and frequent successive 

 geological convulsions and disturbances, which, whilst they have 

 wholly or partially destroyed some of the races most numerous in 

 individuals, have at the same time so broken up the surface of the 

 earth as to afford great facihties for the preservation or isolation of 

 others represented by a comparatively small number of individuals. 

 The consequence is that there is probably no portion of the northern 

 hemisphere in the Old World, of equal extent, where the species 

 altogether, and especially the endemic ones, are more numerous, 

 none, I believe, which contains so many dissevered species (those 

 which occupy several Kmited areas far distant from each other), and 

 certainly none where there are so many strictly local races, species 

 or even genera, occupying in few or numerous individuals single 

 stations limited sometimes to less than a mile. In all these respects 

 the Mediterranean region far exceeds, absolutely as well as rela- 

 tively, the great Russian region, which has three times its length 

 and twice its breadth ; it presents also, perhaps, almost as great a 

 contrast to a more southern tract of uniform vegetation extending 

 across the drier portion of Africa and Arabia as far as Scinde. This 

 diversified endemic and local character exemplified in the plants of 

 the Mediterranean region has, as far as I can learn, been observed 

 also in insects. 



Of the three great European peninsulas which form the principal 

 portion of the region, the Italian is the narrowest and has the least 

 of individual character in its biology ; but it is the most central one, 

 and, including its continental base with the declivity of the Alps, 

 may be taken as a fair type of the region generally ; it is also by 

 far the best-known. Italy was the first amongst European nations 



LINN. PROC. — Session 1870-71. h 



