CORALS OF THE CIXCINNATI GROUP. 193 



Ch.etetes rugosus, Edwards and Haime. 



Plate 21, fig. 2. 



Chivtctm rugosus, Edwards and Haime ; Pol. Foss. des Terr. Pal., p. 268, pi. 20, fig. 6. 

 Moniiculvpora rugosa, Edwards and Haime, Brit. Foss. Corals, p. 265, note. 



Branches cylindrical or flattened, from two to three lines in diameter, 

 dividing dichotomously at short intervals. Corallites polygonal or sub- 

 circular, the average ones varying from six to eight in the space of one 

 line, separated by many exceedingly minute interpolated cylindrical 

 tubuli. Surface exhibiting numerous elevations, which have a height 

 of from one-fourth to one-half line, and are transversely elongated, so as 

 to constitute so many discontinuous transverse ridges. These ridges 

 vary in length, but they do not extend quite round the stems, and they 

 are usually sharp-edged, and placed about half a line apart. The coral- 

 lites upon these ridges are not larger than those on the other parts of 

 the coral. 



This species is in many respects most closely allied to C Dalei, and 

 there is a considerable probability that a series of intermediate forms 

 may ultimately be obtained by which the two species may be united. 

 The present species is distinguished from the preceding chiefly by the 

 elongation of the surface tubercles in a direction transverse to the long 

 axis of the branches ; but in addition to this character there is here an 

 even greater development of the system of minute tubuli between the 

 ordinary corallites than is seen in C. Dalei. 



Locality and position : Cincinnati group, Cincinnati, Ohio. 



Ch^tetes approximatus, Mcholson. 



Plate 21, fig. 3. 



Corallum composed of cylindrical stems, from one and a half to nearly 

 three lines in diameter, dividing dichotomously at short intervals. Cor- 

 allites tolerably thick-walled, oval, sub-circular, or polygonal in shape, 

 from eight to ten in the space of one line, often with excessively minute 

 corallites interspersed amongst them, though these are rarely as abun- 

 dant as in the preceding forms, and may be nearly absent. Surface ex- 

 hibiting a number of small conical or somewhat transversely elongated 

 eminences, which are very slightly elevated above the general surface. 

 These eminences are placed in irregular diagonal rows, separate about 



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