io6 T/IBULATE CORALS. 



information as to the intimate characters of the former, I think 

 it safer to retain Trachypoi'a in the meanwhile as a distinct 

 genus. This genus, as will be abundantly evident from what 

 has been said already, is incontrovertibly referable to the 

 FavositidcE, and is very nearly related to Pachypoi'a, Lindst. 

 If, as is very probable, an examination of the minute structure 

 of Dendropora explicita, Mich., should show that this too is 

 a Favositoid, then the genus Dendropora, Mich, (including 

 Rhabdopora, E. and H.), will have to take the place of Trachy- 

 pora, E. and H., and the classification and arrangement of this 

 difficult group will have been materially improved. 



All the known species of Trachypora, E. and H., are Devo- 

 nian ; but its union with Rhabdopora would extend the range 

 of the type into the Carboniferous, and I possess a specimen 

 from the Wenlock Limestone of Longhope, which appears to be 

 undistinguishable from Dendropora. It is probable, therefore, 

 that the genus will ultimately be shown to range from the 

 Upper Silurian to the Carboniferous ; but its exact limits must 

 remain at present uncertain. 



Trachypora ornata, Rominger, sp. 



(PL v., figs. 3-3^.) 



Dendropora ornata, Rominger, Foss. Corals of Michigan, p. 6i, PI. XXIII., 

 fig. I, and PI. XXIV., fig. 2. 



Spec. Char. — Corallum composed of cylindrical stems, 

 generally about two or three lines in diameter, branching 

 dichotomously at intervals of half an inch or more. The 

 openings of the tubes on the surface are oval or circular, 

 variable in size, the larger ones mostly about two-thirds of 

 a line in diameter, and either raised above the general surface 

 by a projecting rim, or apparently level with it. Openings of 

 the tubes separated by dense calcareous tissue, which is really 

 formed by the thickening of the walls of the corallites, and 

 which may separate the actual orifices to their own diameter 

 or more. The proper walls may or may not be superficially 



