SUB-GENUS HE2ER0TRYPA. i47 



slightly curved ; and they are developed in much larger num- 

 bers in the small interstitial corallites than in the large tubes. 

 Horizon and Locality. — Cincinnati Group, Cincinnati, Ohio. 



Monticulipora (Heterotrypa) implicata, Ulrich. 



(PI. II. figs. 7-7^-) 



Chceietes iiuplicatiis, Ulrich, Cat. Foss. Cincinnati Crroiip, p. 12, 1880. 



Spec. Char. — Corallum dendroid, of small flattened stems, 

 which average about three lines in width, and from a line and 

 a half to two lines in thickness, giving off branches at short in- 

 tervals (PI. II. figs. 7, ']a). The calices are mostly about i-yoth 

 to I -80th inch in diameter, irregularly oval, often indented on 

 one or both sides, thick-walled, with numerous blunt spines pro- 

 jecting from their margins (PI. II. figs, ^b, 'jc). Between the 

 ordinary calices are the occasional apertures of smaller tubes. 

 The average corallites are thin-walled in the centre of the 

 corallites, but become greatly thickened as they approach the 

 surface, the original lines of demarcation between adjoining 

 tubes being never entirely obscured. Smaller corallites are 

 developed in variable number between those of average dimen- 

 sions. Interspersed also in the thickness of the walls of the 

 corallites, or occupying their angles of junction, are numerous 

 circular hollow tubes, the upper terminations of which appear 

 on the surface as the blunt spines previously alluded to. Re- 

 mote, complete, and approximately horizontal tabulae are devel- 

 oped in the tubes, being somewhat more numerous in the small 

 corallites than in the larcje ones. 



Obs. — Not having met with any published account of this 

 species, I am not sure that it has been actually described by 

 Mr Ulrich, to whom we already owe so much excellent work 

 on the fossils of the Cincinnati Group ; but it has been named 

 by him in his Catalogue of the P"ossils of the Cincinnati Group, 

 and Mr Nickles has been good enough to present to me some 

 specimens of it. Under the circumstances, I should not have 



