CORALS OF THE CINCINNATI GROUP. 199 



allied. From C. delicatulus, Nich., with which it is also related, C. gra- 

 cilis is separated by the smaller obliquity of the corallites, and the pres- 

 ence of minute interstitial tubes between the ordinary corallites. The 

 above description is drawn from type specimens kindly furnished for 

 examination by Mr. U. P. James. 



Locality and position: Cincinnati group, Cincinnati, Ohio. 



Ch^tetes delicatulus, Nicholson. 



Plate 21, figs. 9, 9a. 



Corallum very slender and delicate, ramose, of cylindrical stems, which 

 terminate sometimes in thickened, rounded extremities, and which in 

 some cases appear to spring from a horizontal foot-stalk. Stems some- 

 times simple, more commonly branched, the divisions taking place 

 dichotomously at acute angles. Diameter of the stems usually about 

 half a line, sometimes a quarter of a line, rarely two-thirds of a line. 

 Corallites very oblique to the surface of the coral, opening by oval aper- 

 tures, the lengtn of which corresponds with the long axis of the stem 

 and uniforml}' exceeds the breadth. Calices in diagonal rows, about 

 eight in one line, measured longitudinally, and twelve to fourteen in the 

 same space measured diagonally. The calices are all of equal size, and 

 when perfect the lower lip is more or less thin and prominent. The 

 surface is entirely devoid of monticules or elevations of any kind, and 

 there are no very minute tubuli amongst the ordinary corallites. 



This is one of the commonest fossils of the Hudson River group, both 

 in the United States and in Canada, and it is probably identical with 

 one of the forms figured by Hall from the Trenton limestone under the 

 name of C. lycoperdon (Pal. N. Y., Vol. I., pi, 24, fig. Ik, (cset. excl.). 

 From its very minute size, I am left in doubt as to the true position of 

 this abundant little fossil. It is, I think, certainly a Chastetes, and not a 

 polyzoon allied to Helopora, Hall ; and it is most probably the form which 

 has usually been quoted as a slender variety of Stenopora fibrosa, though 

 its characters would in any case forbid its being retained in this jwsi- 

 tion. It most closely resembles Chxtetes gracilis, James, of which it 

 might be supposed to be only a small variety; but it is separated by not 

 possessing any minute tubuli interspersed amongst the ordinary coral- 

 lites, by the much greater obliquity of the tubes, by the greater thinness 

 of the walls of the corallites, and by its uniformly slender habit and 

 stunted growth. From C. Fletcheri, Edw. and Haime, it is at once dis- 



