Die Silurische Fauna des Westlichen Tennessee. 33 



remain spaces filled with a transparent, yellowish brown chalcedony. 

 These spaces are radial and concentric canals. The little stars one is 

 inclined to regard as spicula grouped in that form. It is only surprising 

 that no framework corresponding to the horny skeleton of the typical 

 si^onges is visible between these stars, and that no space is left for such 

 a framework between the thickly crowded stars. At any rate the 

 spongy character of the body is indisputably proved by the above men- 

 tioned inner structure, even though the outward form were not suffi- 

 cient proof thereof. Moreover, there are also European specimens in 

 the diluvial bowlders of the North German plain wliich exhibit pre- 

 cisely the same interior structure, as I have convinced myself from the 

 cut specimens in the Berlin Museum, to which Beyrich called my 

 attention. 



The geognostic position of this species, which had been observed for 

 a long time, and in many places in Europe, was uncertain, until the 

 discovery of it in Tennessee. It is most frequently found as loose 

 bowlder stone in the diluvial of the North German plain, from Holland 

 to Konigsberg. The circumstance, that the other species of the genus 

 Siphonia, to which it was ascribed, all, or at least the great majority, 

 belong to the Chalk formation ; further, the mode of preservation in 

 dark, flint-like silica, which nearly corresponds to the manner of preser- 

 vation of many chalk sponges ; and, finally, its being found with other 

 fossils, demonstrably belonging to destroyed Chalk deposits, made the 

 origin in strata of the Chalk formation probable, and as a matter of fact 

 this origin w*as universally accepted. Hisinger, indeed, mentioned the 

 •species of the Island of Gothland, yet, in accordance with the words 

 "ad littoria maris Gothlandiise rejecta," used to designate w'here it was 

 found, he regarded it as bowlder stone foreign to that place. Accord- 

 ing to the Duke of Leuchtenberg it is found at Pulkowa, near Peters- 

 burg, but even he does not with certainty regard the there contiguous 

 Silurian strata as its original place of deposit. By means of my obser- 

 vation of the species in contiguous Silurian strata, in the State of Ten- 

 nessee, every doubt in regard to the true place of deposit of this species 

 has been for the first time removed. The numerous specimens (26) 

 collected there agree completely with those in Europe. Their size 

 varies, like those of Europe, from a hazelnut to that of an apple. In 

 the larger specimens the crown is often flattened, as if it were eaten 

 out, apparently, in consequence of a disintegration, while the sponge was 

 still alive. Beside the always visible central oj^enings the almost 

 plain surface of the crown exhibits in this case horizontal canals, radia- 

 tino; from the center toward the circumference. 



After the Silurian strata have been determined in America to be 



