On the Mo7iticuUporoids of the Cincinnati Group. 165 



often regularly arranged in Inies. Walls thin. Interstitial tubes 

 present in well preserved specimens, but difficult to detect on the 

 surface. Spiniform corallites to be seen in well preserved speci- 

 mens. 



Obs. This species seems to have been generally free, but in 

 the form described by Mr. Ulrich as Aspidopom parasitica, it seems 

 to become occasionally parasitic. In this form, when the object to 

 which it becomes attached is too small, the edges show a well- 

 marked epitheca, so it may not really be parasitic even here The 

 groups of larger calices scattered over the surface is a well marked 

 feature 



Formation and Locality : Lower Silurian, Trenton Group at 

 Minneapolis, St. Paul and other places, Minnesota. Cincinnati 

 Group, Cincinnati. 



7. VI. ELEGANS, Ulrich. 



Cimtctes elcgans, Ul. Jour. Cin. Soc. N. Hist., II., 130. 1879. 



Discotrypa clcgans, Ul. Ibid, V., 257, 1882. VI., 164, 1883 

 Aspidopora arcolata, Ul. Ibid, VI., 164, 1883. 



Corallum free, thin, circular, from three lines to one and one- 

 half inches in diameter, and about one-fourth of a line thick; the 

 upper side convex, the lower concave, but specimens generally 

 flattened by pressure. Under surface with an epitheca with con- 

 centric and sometimes radiating stride. Upper surface with low, 

 broad monticules, the bases often nearly in contact. Calices sub- 

 equal, oval, elliptical, hexagonal, or rhombic, those occupying the 

 monticules often larger than those on the rest of the corallum. 

 Interstitial cells occasionally present, occupying spaces between 

 larger calices. Walls of corallites moderately thick. Spiniform 

 corallites few to numerous 



Obs. This species is closely allied to the preceding, into 

 which, perhaps, it may run. It can be separated, if at all, by the 

 low, broad monticules and the variable shape of the calices. The 

 main difference to be noted in the form called arcolata is the shape 

 of the cells; but these assume various shapes on the same corallum 

 and so cannot serve as a means of separation. 



Formation and Locality: Lower Siluria;-), Cincinnati Group, 

 Cincinnat', O., and Covington, Ky. 



8. M. LENS, McCoy. 



Edw. and Haime. Brit. Foss. Cor., 266. 1854. (Pub. Lond. 

 Palseontological Society), 



