On the Monticuliporoids of the Cincinnati Group. i6i 



I. M. UNDULATA, Nicholsoii. Monticidipora [Monotnpa) un- 

 dulata, Nich., Pal. Tab. Cor., 321, 1879. Genus Montic. 170, 1881. 



Chivtctcs iindulata, Nich. Geol. Mag. Dec. ii., II., 176, 1875. 

 Rept. on Pal. Ontario, 10, 2,2)-, i875- 



Monoti-ypa undidata, Ulrich. Jour. Cin. S. Nat. Hist., V., 256, 

 1882. 



Corallum forming large, lobed or laterally indented masses, 

 with a maximum diameter of four inches, and a height of about 

 two inches, the upper surface nearly flat. Corallites thin walled, 

 angular and prismatic ; calices sub-equal, with occasional clusters 

 of from six or more, forming small patches, which are faintly or not 

 at all raised above the general surface ; small coralites sometimes 

 present at the angles of junction of the larger tubes. Tabulae few, 

 complete, placed at corresponding levels in contiguous tubes. 



Obs. This form has as yet, we believe, been found only in 

 the Trenton of Canada. A small, spheroidal or hemispherical form 

 found in the Cincinnati Group, was placed by Dr. Nicholson with 

 the uniidata. As it differs from inniulata so much in shape, and as it 

 resembles the next so much, we have placed it there provisionally. 

 Dr. Nicholson did not give this form even a varietal name. The 

 present description is given, so that in case a form similar to it is 

 found in this locality, as is likely to be the case, it can be 

 recognized. 



Formation and Locality. Lower Silurian, Trenton Group, 

 Peterboro, Ontario. 



2. M. TURBiNATA, U. P. James. 



Chcetetes turbinatum,]a.m.ids. ThePalaeon., 11, 1878. 



Monticidipora [Afonotrypa) undulata, Nich. (The hemispherical 

 form.) Pal. Tab. Cor., 321, 1879. Genus Montic. 170, 1881 



ChcTtefcs subglobosus, Ulrich, Jour. Cin. S. Nat. Hist. ,11., 129, 

 1879. 



Afonotrypa subglobosa, Ul., Ibid, V., 256, 1882. 



Corallum free, forming globular, pear-shaped or irregularly 

 rounded masses, from one quarter of an inch to an inch or more in 

 diameter. Surface smooth; calices polygonal or sub-circular, sub-equal, 

 sometimes larger at the base; maculae consisting of groups of six or 

 more slightly larger calices scattered over, and only a little or not 

 at all raised above the surface. A few minute tubes wedged in at 

 the angles of junction of some of the larger tubes. Walls shown 

 in fractured specimens to be strongly wrinkled. Tabulae few in 

 number. (PI. 2, figs, u?, b, c) 



