On the Moiiticidiporoids of the Cincinnati Group. 133 



being apparently absent in Afonticuliporidcv, but present in both the 

 others. Interstitial cells may be absent or present in Mouticiili- 

 poridcr, but are found in both the others. Diaphragms in all are 

 similar. The main feature of the Fistuliporidcc is found in the ves- 

 icular tissue of the interior of the cells, but this is also found in 

 certain species of Monticuliporidcv, as noticed by Nicholson in his 

 sub-genera Prasopota and Peronopora^- and in Eridopora, as given 

 by Ulrich, one genus referred to Ceramoporidce.\ The remaining 

 features are too slight to characterize orders upon, and consequent- 

 ly we propose to disregard these altogether, and place all the gen- 

 era and sub-genera which are to be regarded as valid, in the one 

 family. 



MoNTicuLiPORiD.B, Nicholson. 



Let us now examine the various genera which have at times 

 been proposed for members of this family, and see if the grounds 

 for their formation are well established. 



Hcterot>ypa, Diplotrypa and Monotrypa, were proposed by Dr. 

 Nicholson in 1879;!; for examples of Monticiilipora, which were to 

 be separated as follows: In the first, ffetet otrypa , the corallum has 

 two kinds of tubes, one larger than the other, and both of which 

 have the walls thickened toward the mouth, the apertures being 

 sub-polygonal or rounded. The second, Diplotrypa, also has a 

 corallum with two kinds of tubes, both of which have thin 7C'(r//s at 

 the surface, and are angular or prismatic; the larger corallites are, 

 further, generally gathered into clusters, and form monticules, 

 more or less conspicuous. And in the third one of these, Monotrypa, 

 the cell apertures seem to be all of the same size, have thin 

 walls, and occasionally, a few of a slightly larger size are gathered 

 into monticules. The walls, however, are sometimes thickened, 

 but there are no interstitial tubes. These external features are 

 correlated with certain internal ones, which are only to be studied 

 by microscopic sections, and as it is the object of this paper to 

 furnish descriptions which will enable students to identify species 

 by macroscopic instead of microscopic examination ; and as in 

 two other genera while the external features are like one of the 

 above, the internal ones are different, it is deemed best to disre- 

 gard these three sub-genera and endeavor to arrange the species 

 on another plan. The two others referred to above are Prasopora, 



*Genus Monticul., pp. 202-215. fj- C. S. N. H.. v. 157. 

 JTabulate Corals, pp. 291-293. 



