188 PALEONTOLOGY OF OHIO. 



and the walls of the corallites thus assume a completely cribriform ap- 

 pearance, looking as if composed of a series of vertical pillars (the septa) 

 united by horizontal crossbars. Tabulae, in the specimens observed, im- 

 perfect ; from three to four in the space of one line. 



The examples of this species that have come under my notice form 

 pyriform or sub-spherical masses, sometimes of considerable size. Super- 

 ficially, they nearly resemble the coral which is generally recognized as 

 Columnaria alveolata, both in the general form of the corallites and the 

 dimensions and characters of the septa, but they are sufficiently distin- 

 guished by the mural pores. From all the massive species of Favosites 

 the present species is distinguished by the well marked septa, and the 

 large size and great number of the pores. From Michelinia, again, G. crih- 

 riformis is separated by not having vesicular tabulae, by the larger and 

 more closely set mural pores, and by the better developed septal system. 



In all the specimens I have seen, the tabulae are incomplete, and noth- 

 ing is left of them but their bases. This state of things, however, is 

 quite common in examples of Favosites and Columnaria, and I entertain 

 no doubt but that the tabulae of the present form were in reality com- 

 plete and in all respects w.ell developed. 



Position and hcality: Cincinnati group, near Cincinnati, Ohio (collected by Mr. 

 U. P. James); also in rocks of the same age (Hudson Eiver group), Eiver Credit, 

 Canada. 



Genus CHJETETES, Fischer, 1837. 



(Oryct. du Gt. de Moscow, p. 160.) 



The genera Chsetetes, Fischer, Stenopora, Londsdale, and Monticulipora, 

 D'Orb., comprise a great number of highly characteristic Palaeozoic Corals, 

 which agree with Favosites in possessing a corallum made up of prismatic 

 or sub-cylindrical corallites, without septa, or with these structures in a 

 radimentary form, but with a well developed system of transverse dia- 

 phragms or tabulae. From Favosites the above-mentioned three genera 

 are readily distinguished by the absence of mural pores, but their sepa- 

 ration from each other is a much more dif&cuit matter. As originally 

 defined by Fischer, the genus Chsetetes was separated from Favosites only 

 by the supposed absence of tabulffi in the former ; but Mr. Lonsdale, with 

 his usual acumen, pointed out that the type species of the genus (C. radi- 

 ans, Fischer) was characterized by the amalgamation of the walls of con- 

 tiguous corallites, a peculiarity depending upon their fissiporous mode of 

 increase " by sub-divisions within the area of the parent tube." This 



