14 THE ZOOLOGIST. 



and a portion of the Odenwald in the extreme north, is situated 

 the alluvial Rhine plain, containing the most populous and 

 highly cultivated districts. 



As regards the geological constitution of the Grand Duchy, 

 which has attracted the attention of several eminent writers, 

 little need here be said, as its effects, direct or indirect, upon the 

 organisms distributed over the surface, are easily over-rated, and 

 indeed, in the case of the higher animals, almost nil. It will 

 therefore be sufficient to notice that the more hilly portions of the 

 country are composed chiefly of gneiss and granite, with occa- 

 sional porphyritic formations superimposed, and that among 

 sedimentary rocks the Trias predominates, being represented by 

 large beds of Bunter sandstone (identical with that of the Vosges) 

 and Muschelkalk ; while of particular interest, as affecting also 

 in some degree the distribution of certain species, may be 

 mentioned : — the re-appearance of the oolite as a continuation 

 of the Swiss Jura, pierced by the Danube in its upper course ; 

 the occurrence of pleistocene Loess or fluviatile loam, in portions 

 of the Rhine valley ; some noteworthy tertiary deposits in the 

 South-east ; and, lastly, the elevations of phonolite, dolerite, 

 and other volcanic material of the Hohgau (north of Schaff- 

 hausen), the Kaiserstuhl (between Freiburg and the Rhine), and 

 one or two isolated points. 



Such contrasts of temperature and marked diversity of sur- 

 face and soil may justly be expected to favour the preservation of 

 the rarer indigenous species, while the geographical position of 

 the country has afforded the necessary facilities for the immi- 

 gration, from various points and by various sources, of foreign 

 ones ; and it is to the influence of these factors that we may 

 attribute the richness, in almost all its branches, of the native 

 organic world. 



Referring exclusively to reptiles and amphibians, we find that 

 Baden lays claim to nearly all the German species of the former 

 now recognised, one Chelonian and one Ophidian only being 

 absent from the list. Whereas in this instance we have reason to 

 apprehend that the number may never be augmented, there is 

 some prospect that of the two anurous batrachians, with the 

 presence of which this country is as yet not credited, one or the 

 other may still be discovered. Of tailed batrachians only one 

 sub-alpine form can be cited, to which it is not entitled, 



