Structure of Heteropora neozelanica, Bush 



All 



thus resembling in this region the outer portion of longitudinal 

 sections. The only point to notice about these sections is 



Fig. 4. 



Thin sections of Monticulipora Jamesi, Nich. A. Part of a tangential 

 section, taken just below the surface, enlarged eighteen times, showing 

 the large and small corallites and the interspersed spiniform corallites. 

 B. Part of the same section, enlarged fifty times. C. Part of a transverse 

 section of a branch, in the axial region, enlarged eighteen times, showing 

 the thin-walled, polygonal, and unequal-sized corallites of this part of 

 the corallum. D. Part of a longitudinal section in the median plane, 

 showing the corallites in the outer portion of their course, where tbeir 

 walls are thickened. The section shows the larger and smaller corallites, 

 the former with remote, and the latter with close-set, tabulae. From the 

 Cincinnati group, Ohio. 



that in their central portion we find the axial corallites to be 

 polygonal in shape, and to be bounded by very thin and deli- 

 cate walls (fig. 4, C), which, as before, are wholly imper- 

 forate. There is also now a total absence of the smaller 

 interstitial corallites, these latter being confined to the exterior 

 zone of the branches, and not extending into the deeper parts 

 of the corallum. 



(c) Longitudinal sections show different characters accor- 

 ding to the precise point at which they are examined. In 



