i88 Cincinnati Society of Natural History. 



to one and one-quarter inches in diameter, and from two to 

 six lines or more high ; under surface with a concentrically 

 wrinkled epitheca, generally deeply concave, but sometimes 

 flat ; upper surface with scattered and very slightly raised 

 monticules, composed of corallites slightly above the average 

 size ; corallites directed at nearly right angles to the entire 

 basal plate, to the upper surface, and of two kinds, large and 

 small, and both intermingled ; large tubes more or less thin- 

 walled, angular, sub-angular, or hexagonal, sometimes in 

 groups of four or five each ; small corallites very numerous 

 and variable in size and form, always thin-walled and angular, 

 filling the spaces between the larger tubes ; spiniform coral- 

 lites at the angles of junction of the cells ; in internal sections 

 all the tubes except the spiniform corallites equally thin- 

 walled, the large corallites crossed b}- remote, horizontal and 

 complete tabulae, the smaller ones by similar but more closely 

 set tabulae. (Pal. Tab. Corals, 1879, pi. XIII, fig. 4,4 b; 

 Genus Montic, 1881, p. 160.) 



Locality. — Warren and Clinton Counties, Ohio. 



Remarks. — This is one of the numerous forms that have 

 been referred to petropolilanus Pander, and it is puzzling 

 because of the similarity in external form to several other 

 species. In an article published in 1888,* by U. P. and J. F. 

 James, the species described by Nicholson as M. sehcyuii was 

 placed as a synonym of the present form. The internal struc- 

 ture of the two is different, so that it seems best to separate 

 them. AI. sehcy^iii \\.sq\{ does not seem to occur at Cincinnati, 

 but a variety of it does. This will be referred to later on. 



16. — M. ciNCiNNATiENSis James, 1875. 



Corallum either free or attached, forming a layer a line or 

 less thick ; under surface with a strongly-wrinkled epitheca, 

 not often seen ; upper surface covered with numerous conical 

 and very prominent monticules, the bases of which are close 

 together; calices sub-polygonal, moderately thick walled, 

 with a number of interstitial cells; corallites of two kinds; 

 the larger generally oval or circular, the smaller variable in 

 shape, but more or less angular ; vertical sections show the 



■^'Jour. Cin. Soc. Nat. Hist., vol. Ui, Jan., 1.^88, p. 10'.). 



