igS Cincinnati Society of Natural History. 



S2ibpla7ia, Ulrich. Jour. Cit\. Soc. Xat. Hist., vol. 5, 1883, 



P- 253)- 



Locality. — Cincinnati, O., Covington, Ky., etc. 



Remarks. — As noted above this species was originally con- 

 sidered a variety of M. onealli, but it was afterward raised to 

 the rank of a species. Some of the distinguishing features 

 are the larger calices in the macula:, the greater number of 

 interstitial corallites and the much more robust mode of 

 growth. Mr. Ulrich's species, subplana, seems to be the same 

 as commicnis, and for comparison the main features of his 

 description are given below. 



Callopora subplana Ulrich. Corallum ramose, branches 

 cylindrical, from two to five lines in diameter and dividing 

 dichotomously at intervals of six lines to one inch ; surface 

 showing clusters of from four to eight cells larger than the 

 rest and often raised above the general surface ; calices polyg- 

 onal when unworn; but sub-polygonal or rounded when 

 worn ; interstitial cells few, most numerous between the 

 large cells of the maculae ; longitudinal sections show the 

 corallites in the axial region to have very thin, crimped 

 and flexuous walls ; tabulae here are few but become more 

 numerous toward the surface, where also the walls are 

 thickened and interstitial tubes make their appearance; 

 tabulae in these last always complete and crowded ; in 

 tangential sections corallites rounded or oval with thick- 

 ened walls ; walls fused so the boundary can not be de- 

 tected, but the cavity of the tubes surrounded by a sec- 

 ondary deposit of concentrically laminated sclerenchyma, 

 the original wall represented by sclerenchyma of a lighter 

 color; interstitial cells variable in size and shape, less numer- 

 ous than the proper corallites. 



24. — M. IMPERFECTUM Ulrich (sp.), i8go. 



Corallum dendroid, branches sub-cylindrical, robust, 20 

 mm. or more in thickness, dividing at short intervals; surface 

 marked with very slightly elevated aggregations of larger 

 cells surrounding a cluster of smaller cells; calices sub- 

 circular; corallites with thin walls, very little thickened in 

 the peripheral region ; sub-polygonal ; interstitial cells few, 



