On the Montiadiporoids of the Cincinnati Group. 179 



stood that no absolute assertion is made by me as to the real 

 distinctness of the forms here described under distinct names. I 

 have had the opportunity of examining very extensive collections 

 of these corals, and have been enabled to separate certain examples 

 which present characters sufficiently distinct to be recognized with- 

 out difficulty by the practiced observer, but I am far from asserting 

 that still more extensive collections might not show a graduated 

 series, of intermediate forms uniting the apparently distinct types 

 with one another. As regards C. pidcheUus, at any rate, it is cer- 

 tain that, whilst the type specimens of the species can be recognized 

 without the smallest difficulty, it is a matter of impossibility to 

 determine, with the materials at present in our hands what are the 

 true limits of the species. Thus, specimens apparently belonging 

 to C. pidchellus may be picked out which approximate to C. ap- 

 proximatus, Nicholson, and which thus tend toward the type of C 

 Dalei Ed. and H., since they' possess tolerably distinct surface 

 tubercles. [C approxiviatiis is now regarded as a synonym of ^(7/^/, 

 which itself is an indistinct variety of ra}nosa.^^ Others approach 

 C. flctcheri, E. and H. [now M. ulric/n, Nich.] so nearly, that it 

 becomes absolutely out of the question to draw a rigid line of 

 demarcation between the two species, certain specimens being just 

 as properly referred to one as to the other. In this way C. pidchel- 

 lus is brought into direct connection with C. gracilis, James, though 

 the typical examples of the two species could not be confounded 

 with one another for a single instant. Again, the forms which I 

 have here separated under the name of C. sidpidchclliis form an 

 unmistakable transition between C. pidciiellus, in its proper form, 

 and C. mavDuidatiis, Ed. and H., the latter belonging to the 

 frondescent and laminar section of the genus."* These remarks 

 indicate the close similarity of many of these species. The author 

 may have changed his opinion in regard to some of them, but the 

 fact itself has not been altered, that there are many difficulties in 

 the way of separating various forms. This one is principally to be 

 recognized by the maculae of large cells and the small number of 

 interstitial corallites. 



Formation and Locality : Lower Silurian, Cincinnati, Group, 

 Cincinnati, Ohio. 



26. M. ULRicHi, Nicholson. 



Monficidipora {Heterotrypd) ulrichi, Nich. Genus Montic, 131, 

 1881. 



*Pal. Ohio, It., 195-96. 



