Die Silurische Fauna des WestUchen Tennessee. 29 



From Die Silurische Fauna des WestUchen Tennessee. By Dr. Fee- 

 DiXAND RcEMER. [Trail. -latetl by Thomas Vickeus, for tliis 

 Journal.] 



I. Spongke. — The occurrence of Spongue in the older formations, 

 down as far as and including the Zechsteui, is very rare, when we com- 

 pare it with the frequency of these bodies in certain divisions of the 

 Jura and Chalk formations, and in the seas of the present epoch. From 

 the Zerhstein we know, through King, of a few ill shaped and badly 

 preserved forms, concerning which, in part at least, it is still doubtful 

 whether they belong to the Spongke. In the carboniferous group no 

 remains have hitherto been found which can with certainty be said to 

 belong to this class. In the Devonian rocks, their appearance, aside 

 from a few altogether doubtful substances, is limited to a small species, 

 described by the brothers Sandberger as Scjjplua constricta^ occurring 

 in the limestone of Vilmar; its state of preservation, however, like 

 that of all the fossils in the above locality, is so unfavorable, that in 

 this case, also, there are still doubts as to its really belonging to the 

 sponges. It is only the Silurian series that can show any considerable 

 number of undoubted Spongke. Hitherto, it is true, they have been 

 observed only in isolated places. Several larger species are found in 

 an accumulation of Silurian diluvial bowlders, near Sadewitz, not far 

 from Oels, in Silesia, of which Oswald has given a description, and for 

 some of which he has created the genus Aidocopium. More numerous 

 and better preserved are the species of our fauna from Tennessee, 

 which I am about to describe. That they b^ong to the Spongice is 

 just as certain as the Silurian age of the strata in which, they are 

 embedded. They are petrified, as most of the sponges of the Chalk 

 and Jura formations are, and exhibit in their interior a texture alto- 

 gether analogous to the later sponges, perforated by canals, and the 

 interstices filled with countless little spicula, grouped in the form of 

 stars. They lie in the same calcareous strata with numerous un- 

 doubted Silurian Crustacea, crinoids, and zoophytes, and are frequently 

 found embedded in the same piece of rock with the latter. The fre- 

 quency of the individuals is so great that they form an essential part 

 of the fauna. It is surprising that they are not found in the precisely 

 contemporaneous strata of the State of New York (Niagara Group of 

 the New York State geologists), though numerous fossil species are 

 identical in the two formations, nor in the contemporaneous Wenlock 

 limestone of England. On the other hand, however, from the lime- 

 stone of the Island of Gotland, which otherwise so nearly resembles 

 that of Wenlock, we have the A^tylospongki pnemorsa, and another 



