> Lower Ludlow. 



36 GEOLOGICAL MEMOIRS. 



seventy, this number including only those which have well-marked 

 and constant specific characters. 



Notwithstanding this great abundance of Cephalopodous remains, 

 there are very few species which can be identified with those of 

 other countries. In the absence of sufficiently good specimens, 

 the author, judging from the figures in the ' Silurian System,' makes 

 the following identifications : — 



Orthoceras Ibex Upper and Lower Ludlow. 



0. distans? 



0. diraidiatum ? 



O. ludense? 



O. annulatum, M-C 



Gomphoceras pyriforme.... 



Phragmoceras ventricosum . 



P. (Cyrtoceras) arcuatum . 



P. (Cyrtoceras) compressum ...J 



Orthoceras nummularius Wenlock shale. 



It will be seen that species belonging to different stages of the 

 Upper Silurian rocks of England are brought together in the Bohemian 

 limestones. These do not admit of subdivision, for the distribution 

 of Cephalopoda varies much less in vertical range than according to 

 local peculiarities. 



The Orthoceratites are present in such a multitude of species, 

 and the number of individuals is so great, that the calcareous beds 

 are filled with their remains. This genus was evidently prepon- 

 derant during the deposit of the group of beds now under discussion. 



The genus Phragmoceras was considered by Sir R." Murchison 

 as very characteristic of the Lower Ludlow rocks, but in Bohemia 

 it appears lower down, and at the base of the calcareous deposit. 



The family of Brachiopoda was little developed in the beds of 

 this group, in comparison at least with its extent in the overlying 

 beds. The following species found in Bohemia are common to that 

 country and England. 



Terebratula prisca Upper Ludlow. 



T. imbricata ~\ 



Leptsena euglypba >• Lower Ludlow. 



L. depressa J 



To which we may add a Terebratula resembling T, navicula, and 

 called by the author T. altidorsata ; it belongs to a very low portion 

 of the group. 



With the exception of T. prisca, which traverses two of the 

 author's groups, the brachiopods are peculiar to the lower limestones 

 of Bohemia, whilst they are variously distributed in England. 



Many bivalves observed by the author are not alluded to for 

 want of materials of comparison in other countries. He mentions 

 however the Cardiola, of which there are five or six species, two of 

 which, C. interrupta and C. fibrosa, characterise the Lower Ludlow. 

 The genus is confined in Bohemia to the lower limestone. 



The author here mentions the presence in Bohemia of a number 



