164 Cincinnati Society of Natural History. 



Chcetetcs discoideiis, James. Cat. Fos.s. Cin. Gr. , 187 1, (Named 

 but not figured or described.) Nicholson, Quart. Jour. Geol. Soc, 

 XXX., 511, 1874; Pal. of Ohio, II., 206, 1875; '*^""- ^^t. Hist, 

 ser. 4, XVIII., 88, 1876. 



Amplcxopora discoidea, Uhich. J. C. S. N. H., V., 255-56, 

 1882. 



Lcptrotrypa discoidea, Ulrich. Ibid, VI., 158, 1883. 



Corallum free, discoid, concavo, or plano-convex, sharp edged, 

 from five to eight lines in diameter, and about one line in thickness 

 in the centre. Under surface generally concave, covered with a 

 thin, smooth and irregularly striated epitheca, usually with two or 

 three marked, concentric wrinkles. Upper surface, carrying the 

 calices, gently convex, and without any monticules. Calices poly- 

 gonal, sub-equal, occasionally collected into maculre. Walls thin. 

 No interstitial cells. Spiniform corallites situated at the angles of 

 junction of the cells. 



Obs. Ihis species is easily recognized by the disk-like form 

 of the corallum, with the under surface concentrically striated, 

 and the upper one smooth, and with polygonal calices. Prof. 

 Nicholson, in the Ohio Palaeontology, suggested that possibly this 

 was the young of Chcetetes petropolitanus, but has later (Genus Mon- 

 ticulipora, as above), considered it well defined 



Formation and Locality. Lower Silurian, Cincinnati Group, 

 Cincinnati, O. Hudson River Group at Weston, near Toronto, 

 Canada. Also in Trenton Group, Galena Limestone and Hudson 

 River Group, of Wisconsin (see Geol. Wis., IV., 351, 1882.) 



6. M. NEWBERRVi, Nicholson. 



MonticuUpora (Frasopora) neivberryi. Nich. Genus Montic. 

 212, 1881. 



Ch(etetes ?ie7i.>benyi,W\c\\. Pal. Ohio, II., 212, 1875. 



Prasopora (?) newbenyi, Nicholson. Ulrich, Jour. Cin. Soc. 

 Nat. Hist., VI., 165. 1883. 



Aspidopora nevberryi, Nich. Ulrich. 14th Ann. Rept. Geol. 

 & N. Hist. Sur. Minn., 91. 1886. 



Aspidopora parasitica, Ulrich. Ibid, 90. 1886. 



Prasopora contigiia, Ulrich. Ibid, 87. 1886. 



Corallum forming a thin, sub-circular or semi-circular ex[)an- 

 sion, occasionally seemingly parasitic, but generally free, the under 

 surface having a thin epitheca. Upper surface smooth, but with 

 groups of corallites larger than the average, and these at times 

 forming low monticules. Calices polygonal, sub-quadrate, or oval, 



