Devon and Cornwall, Belgium, the Eifel, 8^c. 403 



types are mere general results founded on actual observation, 

 it is obvious that they can never upset conclusions drawn from 

 the clear and unambiguous evidence of sections. The two 

 methods may be used independently, and conspire to the 

 same end, but in their nature connot come into permanent 

 collision*." In the present case it should be borne in 

 mind that the consecutive series of the older stratified rocks 

 of the south of Ireland is unconformahly overlaid in the 

 northern parts of Kerry, Cork, and Waterford, directly 

 either by the true old red sandstone formation of British 

 geologists, or by the carboniferous limestone, or the coal for- 

 mation f. 



I might now extend the comparison by entering into the 

 countries adjacent to the right bank of the Rhine, or into 

 the Fichtelgebirge ; but in neither of them is the informa- 

 tion hitherto obtained of so extensive and detailed a character 

 as to admit of precise conclusions. To what was previously 

 known respecting the former tracts, M. Beyrich has made 

 considerable additions in his Beitrage; and from these con- 

 tributions it may be collected, that the greater part of the 

 Nassau limestones near Dillenburg, &c., as well as those of 

 Bensberg, Refrath, PalFrath, &c., adjoining the Rhine, to- 

 gether with the greywacke and slaty rocks in which they are 

 intercalated, or on which they simply rest, exhibit in general 

 the same organic remains as the Eifel, although they possess 

 also species and even genera not hitherto found in the latter; 

 e. g., at Paffrath the genera Nerita, Megalodon, Cardita, 

 Monodonta, Buccinum-, and in Nassau in the Wissenbach 

 clayslate Parmophorus ; and in the limestone on the Lahn near 

 Villemar an Ostrea, a genus not previously noticed in any 

 transition country. Of the Nassau limestones it is remarked 

 that they differ chiefly from the Eifel limestone by being for 

 the greater part interstratified with the greywacke and slate 

 rocks, while the limestones of the Eifel are merely superim- 

 posed upon the latter in troughs. In Belgium, however, the 

 same, namely, the lower limestone of that country, forms an 

 interstratified portion of the general series. Considering then 

 the fossils which have been noticed in these districts, we have 

 here again an exemplification of affinities and differences in 

 the organic types of their respective strata. Should M. 

 Beyrich complete the work which he proposed to himself in 

 the year 1837, of drawing up an exact critical catalogue of 



* Proc. of Geol. Soc, vol. ii., p. 675, May 1838, [or Lond. and Edinb. 

 Phil. Mag. vol. xiii., p. 299. 



f See my Geological Map of the South of Ireland, in Geol. Trans, 

 vol. v.j second series. 



