208 



THE GENUS MONTICULTEORA. 



internal structure. The large corallites are, on the whole, 

 rounded, with distinct walls, and invariably showing the 



Fig. 44. — A, Outline of a large specimen of RIontictdipora Sehvyiiii, Nich., from the Trenton 

 Limestone of Ontario, viewed in profile. B, Tangential section of the same, enlarged 

 eighteen times, showing the two sets of corallites, and the incomplete tabula? of the large 

 tubes : one of the groups of small corallites is also shown in the section, c, A small por- 

 tion of the preceding section, enlarged fifty times. D, Vertical section of the same, en- 

 larged eighteen times, showing the peculiar double tabulation of the large tubes, and the 

 close-set complete tabulae of the small tubes. The section passes in part through one of 

 the groups of small corallites. 



peculiar feature that the visceral chamber is intersected by a 

 crescentically incomplete tabula, the true structure of which is 

 fully brought out in vertical sections. The small tubes fill all 

 the interspaces between the large corallites, but vary very much 

 in amount in different sections, being, however, always more or 

 less angular in shape. In some specimens the number of the 

 interstitial tubes is comparatively small, whereas in others there 

 is a very extensive development of these intermediate corallites. 



