On the Moiitiailiporoids of the Cincinnati Group. 171 



seen. Upper surface covered with numerous conical and very 

 prominent monticules, the bases of which are close together. 

 Calices sub-polygonal, thick walled, with a moderate number of 

 interstitial cells. Corallites of two kinds; the larger generally 

 oval or circular, the smaller variable in shape, but more or less 

 angular. 



Obs. This species is readily recognized by the very prominent 

 conical monticules of the upper surface, there being no other 

 species of the discoid group which has such prominent elevations 

 on the surface. Of Af. consimilis there was but a single frag.nent- 

 ary specimen found, and we believe ourselves justified in placing 

 it here as a synonym. Prasopora nodosa is undoubtedly the same 

 as cincinnatiensis, tliough from another horizon. Mr. Ulrich has 

 seen fit (J. C. S.N. H. V. , 239) to disregard the fact that the sjjecies 

 under notice was named and described by one of us, and he has 

 placed Nicholson's name after it as authority. This, either inten- 

 tional or accidental, he has repeated in other species, a course 

 which is as unjustifiable as it is unjust. It is here noticed in order 

 that it may not mislead future students. 



Formation and Locality : Lower Silurian, upper part of Tren- 

 ton Group, at Nashville, Tenn. Cincinnati Group, at Cincinnati 

 and Oxford, O. • 



Group I IL Dendroid or Ramose ; branching more or less ; stems 

 cylindrical or sub-cylindrical; base free or attached; calices cover- 

 ing the branches, varying in form : monticules present or absent. 

 L Surface smooth. 



a. calices oval or circular; all similar. 



* apertures of calices thick 15 



'>-' apertures oblique ; lips thin 16 



b. calices oval or circular; interstitial cells present. 



^' apertures oblique; lips thick 17 



* macule present, with larger cells than average; lips 



thick , 18 



* larger cells separated by number of small ones. . . 19 



* maculae present; made of larger cells, and occupied 



also by minute cells 20 



* calices surrounded by ring-like wall 21 



c. calices rhomboidal; arranged in lines. .22 



d. calices irregular in form 23, 24 



