368 Observations upon Stenopora fibrosa, etc. 



Observations upon Stenopora fibrosa and the genus Chetetes. 

 No class of fossils found within the Cincinnati Group has been regarded 

 by collectors with the same degree of uncertainty, as the corals. No 

 one scarcely has relied upon the name by which any coral found at the 

 Cincinnati quarries was known, save, perhaps, two or three species. 

 And, as the sequel will show, this uncertainty, strange as it may seem, 

 has not been without foundation. The most common coral, yea, the 

 most common fossil in the group, has hitherto borne the name of a 

 genus that has never been found within it, and likewise Avorn an erro- 

 neous specific name. And, yet, this same coral was the second fossil 

 collected and described from this locality. The Isotehis gigas was pub- 

 lished by DeKay in 1824, and the Calamopora fibrosa by Goldfuss, in 

 1826. 



After the most careful examination of hundreds of specimens, pol- 

 ished and unpolished, fractured and weather-worn, under the most 

 favorable circumstances, the fact that no coral possessing the generic 

 characters of Chetetes 'was ever found within the Cincinnati Group seems 

 too clearly established to leave a remnant of doubt upon the subject. 

 And that the corals which have been generally known under the gen- 

 eric name of Qietetes belong to the genus Stenopora seems quite clear. 



The genus' Chetetes was founded by Fisher in 1837, upon the type 

 species C. radians, obtained from the carboniferous rocks of Russia. 

 It is an essential generic characteristic that the walls of the tubes are 

 inseparably connected together, owing to the fissiperous method of 

 reproduction. Now, the walls of the tubes of the corals from the 

 Cincinnati Group readily separate, and the evidences are incontestible 

 that the method of reproduction was exclusively gemmiparous. 



For this reason, the Chetetes peiropolitanus, found in the Lower Silurian 

 rocks of Russia, in which Lonsdale discovered the divisional lamina of 

 one tube developed within the area of one which preexisted, does not 

 exist in this locality. 



For the purpose, however, of more clearly establishing this fact in 

 the mind of the reader, the generic characters of Stenopora and Chetetes, 

 as well as the specific characters of fibrosa and petropolitanus, are here 

 reproduced, with the remarks of Lonsdale upon the generic characters 

 of Chetetes. 



Genus Stenopora — (Lonsdale). 



Pol^podom polymorphous, composed of round or polygonal tubes, radi- 

 ating from an imaginary axis to the surface, where the bounding ridges 

 are tuberculated ; young tubes interpolated by latei-al budding 



