GENERA OF CH.ETETID.E AND MONTICULIPORID.E. 



!8l 



lae." The "monticules" or " mamelons " are circumscribed 

 areas on the surface of the corallum, which are, typically, ele- 

 vated so as to form a series of rounded, oval, or elongated 



Fig. 38. — A, Vertical section of a few of the corallites of Stenopora lasinaniensis, Lonsd., in 

 the final portion of their course, enlarged twenty times, showing the annular thickenings 

 of the tubes and the remote tabulae ; B, Tangential section of the same, taken just below 

 the surface, similarly enlarged, showing the transversely divided spiniform corallites be- 

 tween the ordinary tubes. Carboniferous, Australia. 



projections, but which may be nearly or quite level with the 

 general surface. Sometimes the " monticules " are composed 

 of corallites which differ in no conspicuous feature from those 

 which form the rest of the coral (e.g., in J/, ramosa, D'Orb.) ; 

 in other cases {e.g., M. piilchella, E. and H.) the corallites 

 which form the " monticules " are of a markedly larger size 

 than the average; while in still other forms [e.g., M. froiidosa, 

 D'Orb.) the "monticules" — in this case flat — are occupied by 

 corallites much more minute in their size than those which 

 form the bulk of the colony. The so-called " maculae " are 

 simply " monticules," in which the mouths of the tubes have 

 become closed by a calcareous membrane. 



The only other point as regards the structure of the Monti- 

 cidipoi^cE which need specially be noticed here concerns the dis- 

 position of the tabulce. These structures are invariably present 

 in the typical Monticitliporcr, and are almost invariably " com- 



