20 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June S, 



north) would be quite enough to fix the age of these rocks as being 

 the same as the limestones of Wenlock and Dudley. The collection 

 in the town of Wisby is indeed so amply supplied with fossils from 

 the surrounding localities as to render quite certain the identification 

 of the limestone and shale of the north of Gothland with the Wenlock 

 limestone and shale of England. In short, I doubt if in any other 

 quarter of the globe two synchronous deposits can be found, which, 

 900 miles apart in a straight line, are so closely assimilated as the 

 Wenlock and Wisby limestones, both by mineral characters and fossil 

 contents. 



Thus, among the Wisby Encrinites is the remarkable Hypantho- 

 crinites decorus ; among the Trilobites, the Calymene Blumenhachii ; 

 among the Orthoceratites, the Orthoceratites annulatus and O. ibex ; 

 and among the Euomphali, the E. rugosus (JEJ. catenulatus. Dalm.), 

 together with the Pentamerus galeatiis, Atrypa tumida, and nume- 

 rous other shells, whereof a list is annexed, which are typical Wen- 

 lock forms. 



On the east coast of the northern part of Gothland we visited the 

 bay and port of Slite with its promontories and islands, where the 

 same rock is burnt for lime, and whence it is largely exported. Tiiis 

 rock, nearly as white as chalk when viewed at a distance, exhibits in 

 its interior very much the same general appearance as certain varieties 

 of the Wenlock limestone of England, wherein concretions or "ball- 

 stones " of greenish, greyish and pinkish colours, and loaded with 

 corals, encrinites, &c., are irregularly wrapped round by partings or 

 way-boards of greenish or ash-coloured shale. 



It is on the western shore of the fine land-locked bay of Slite, that 

 portions of this rock stand out in those grotesque masses of limestone 

 which were rudely figured by Linnaeus in the description of his tour 

 in Gothland. These rocks of Lanna are in fact dismantled portions 

 of former hard coralline reefs, the earthy and softer portions of 

 which have been worn and washed away. The highest of these 

 masses may be from thirty to forty feet high, and they consist of the 

 small concretionary, coralline, marble-like limestone of pinkish and 

 grey colours, each great mass being, in fact, a huge ball-stone 

 traversed by irregular lines of fracture, and presenting in one point 

 of view the appearance given in the drawing (PI. I. fig. 10). 



Whilst however not a shadow of doubt could exist (even before 

 our visit) respecting the age of the great mass of limestone and shale 

 of the north of Gothland, the interesting point before alluded to re- 

 mained to be determined, namely whether the southern and south- 

 eastern portions of the island that terminate in the rocky promontory 

 of Hoburg might not (as I had supposed) be referred to a still higher 

 member of the Silurian system, and be in fact the equivalent of the 

 Ludlow formation of Britain. To answer this question, M. de 

 Verneuil and myself, escorted by Baron Fock, travelled from Wisby 

 to Mount Hoburg and the adjacent tracts. 



The general results of our survey are explained in the diagram 

 (PI. I. fig. II) ; though it must be understood that this section, ex- 

 tending over a distance of about fifty miles in a very flat region, is 



