CORALS OF THE CINCINNATI GROUP. 211 



pressed tubercles, which are all drawn out in one direction, and which 

 are occupied on their sides by the ordinary corallites, though sometimes 

 more or less compact at their summits. The long diameter of these 

 tubercles varies from two-thirds of a line to two lines, their width not 

 exceeding half a line, and their height being variable (usually equal to 

 the width). They are arranged in tolerably regular diagonal lines, from 

 half a line to two-thirds of a line apart. The corallites are thin-walled, 

 polygonal, sub-equal, from eight to ten in the space of one line, appar- 

 ently alogether without any intermediate tubuli. There are also no 

 groups of large sized corallites. 



This very distinct species is related to C. papillatus, McCoy; but is 

 sufficiently separated by the long, narrow tubercles, which do not carry 

 large sized corallites. All the specimens which I have seen are in the 

 form of thin and extended crusts, growing parasitically upon the exte- 

 rior of Orthocerata. In some examples, the tubercles are depressed (prob- 

 ably from attrition), and appear to be nearly solid, but they are more 

 commonly strongly elevated, and carry corallites of the ordinary dimen- 

 sions on their sides. 



Position and locality : Cincinnati group, Cincinnati, Ohio. Collected by Mr. U. P. 

 James. 



Ch^tetes Ortoni, Nicholson. 



Plate 22, figs. 3, 36. 



Corallum forming exceedingly thin crusts, not more than from one- 

 sixth to one-eighth of a line in thickness, growing parasitically upon 

 foreign objects. Crusts usually forming a circular expansion, half an 

 inch or more in diameter, sometimes irregular and indefinite in outline: 

 Surface exhibiting numerous minute rounded or conical eminences, 

 placed at distances apart of half a line, less or more. Tubercles usually 

 more or less compact at their summits, carrying on their sides corallites 

 which are little or not at all larger than the average. Corallites some- 

 what oblique to the surface, moderately thick-walled, sub-equal, without 

 any intercalated very minute tubuli. Calices small, sub-polygonal, from 

 ten to twelve in the space of one line, their margins thick and sur- 

 mounted by very minute and crowded miliary tubercles, which are 

 rounded and not spinous, and are placed almost in contact with one 

 another. 



In external appearance, this species, but for its excessive tenuity, and 

 the close-set, pointed and conical tubercles, might be taken as the young 



