CORALS OF THE CIXCINNATI GROUP. 197 



This species is closely allied to C. jmlchellus, Edw. and Haime, but ap- 

 pears to be distinguished sufficiently from it by the flattened and com- 

 pressed form of the branches, and the composite character of the hardly 

 elevated tubercles which do not consist throughout of large sized coral- 

 lites, but have an external ring of large tubes surrounding an internal 

 cluster of very minute tubuli. I have found these characters constant 

 in a large number of individuals, and consider, therefore, that I am jus- 

 tified in describing this form under a distinct title. 



The above description is founded upon specimens collected by Prof. 

 Edward Orton and Mr. U. P. .James, and kindly submitted to me for 

 examination. 



Locality and podtion: Cincinnati group, Cincinnati, Ohio. 



Ch.etetes Fletchert, Edwards and Haime. 



Plate 21, figs. 7, 7a. 



Calamopora spongites ? var. Goldfuss, Petref. ; pi. 64, fig. 10 (in parte). 



Favosites spongites (pars) Lonsdale; Sil. Syst., pi. 15 bis., figs. 9, 9a, 96 (c£et. excl.). 



Chietetes Fletcheri, Edw. and Haime; Pol. Foss. des Terr. Pal., p. 271, 1851. 



Chietetes lycopeulon, Hall (pars) ; Pal. N. Y., Vol. II., pi. 17, figs. Ig-i (cset. excl.). 



Mordiculipora Fletcheri, Edw. and Haime; Brit. Foss. Corals, p. 267, pi. 62, figs. 3, oa. 



Corallum ramose, branches cylindrical, or sub-cylindrical, dividing 

 dichotomousl}^ at remote intervals, often irregularly swollen at short 

 distances, from one and a half to three lines in diameter, not uncom- 

 monly hollow. Corallites circular or oval, with comparatively thick 

 walls, unequally sized, those of average dimensions being from eight to 

 ten in the space of one line. Interspersed with the ordinary' corallites 

 are exceedingly minute cylindrical or polygonal tubuli, sometimes in 

 small numbers, and at other times in great plenty. Surface smooth and 

 entirely destitute of elevations or tubercles, but occasionally showing 

 groups of corallites the size of which is very slightly larger than the 

 average. 



The examples of C. Fletcheri, which I have examined from the Clinton 

 group of Canada, agree entirely with the description given by Edwards 

 and Haime, being smooth, and simply having very minute corallites in- 

 tercalated amongst those of ordinary size. On the other hand, most of 

 the examples of this species which I have seen from the Lower Silurian 

 strata of Cincinnati, though also smooth, and also having minute tubules 

 interspersed amongst the larger corallites, exhibit distinct groups of cor- 



