134 Cincinnati Society of Natural History. 



Nich. and Eth., Jr., 1877, and Pcronopora, Nich., 1881. The 

 first of these, Pi'asopora, was at first regarded as a genus distinct 

 from Moiiticidipora.'^^ But afterward,! it was reduced to the same 

 rank as the others, and regarded as a sub-genus. It, like Diplo- 

 trvpa, has two kinds of coralHtes, large and small, and these have 

 their walled tubes, also as in Diplotrypa, and the genus is mainly 

 separated from the others by having internally a number of vesic- 

 ular spaces along the tube walls, in addition to nearly horizontal 

 tabuLne. Finally, in Pcronopora, we have the same dimor|)hic cor- 

 allum, this time with thickened walls, and also the vesicular inter- 

 nal structure. + At the present writing we chink these sub-genera 

 had better be abandoned. 



We come now to examine the characters of a host of genera 

 proposed by Mr. E. O. Ulrich in his papers on "American Palae- 

 ozoic Bryozoa."^ As the title of his papers indicates, Mr. Ulrich 

 regards the Monticiiliporoids as Bryozoans, a position in which we 

 do not follow him, and which opens up a question already referred 

 to, and which can not be properly discussed here. We shall ex- 

 amine the descriptions which he has given of these new genera, 

 and think that we can show that none of them are of sufiticient 

 value to stand. 



Monotrypclla, Ul., is defined as being "ramose, smooth or 

 tuberculated, cells apparently of one kind only. Walls very thin 

 in the axial portion of the branches, but much thicker in the peri- 

 pheral region. Diaphragms straight. No spiniform tubuli" [cor- 

 allites].|| The resenblance to Monotrypa, Nich., is seen in the 

 one kind of corallites, and the difference is only the thickening of 

 the cell walls at the mouths. This occurs in so many genera, and 

 in such varying degrees, that of itself it can not be considered of 

 any importance. Taken in connection with the one kind of cor- 

 allites, it approaches too closely to Mofiottypa, especially as in^the 

 diagnosis given by Nicholson of his genus, it is stated that in some 

 cases the walls of the corallites are appreciably, or even consider- 

 ably, thickened; but they always preserve in such cases the original 

 lines of demarcation separating the adjoining tubes. "^ 



Amplcxopora, Ul., differs only from Monotjypella in having 



*Am. Nat. His., Ser 4, XX.. 3SS. f'al. Tab. Cor., p. 324. 



-[•Genus Montic, 202. 



Jlbid, p. 215. 



$J. C. S. N. H., V. VI. 188^-83. 



IIJ. C. P. N. H. Ibid v., p. 153. 



ITGenus Montic, p. 16S. 



