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CHAPTER X. 



Sub-gen7is Peronopora, Nich., iSSr. 



I PROPOSE the sub-generic name of Peronopora for a peculiar 

 group of Monticuliporoids in which the corallum is either 

 laminar or encrustino-. Two distinct sets of coralhtes are 

 present, distinguished by their size and internal structure. 

 The large corallites are furnished with incomplete tabulae of 

 the type of those found in the corresponding tubes of Praso- 

 pora — that is to say, the tabulae form a series of lenticular 

 vesicles on one side of each large corallite, these vesicles 

 limiting an excentric lateral tube, which is crossed by a few 

 complete horizontal plates. The small corallites are numerous, 

 interspersed among the larger ones, sometimes partially aggre- 

 gated into clusters, their tabulae being always numerous, close- 

 set, horizontal, and complete. Spiniform corallites are usually 

 largely developed, though occasionally apparently wanting 

 {e.g., in Af. molesta, Nich.) The walls of the corallites are 

 thickened and seemingly fused together in adjoining tubes, 

 their primitively duplex character being entirely lost. Type 

 of the group, M.frondosa, D'Orb. { = M. decipicns, Rom.) 



The species of this section are distinguished from those of 

 all the other groups of Monticulipora, except Prasopora, by 

 the peculiar structure of the tabulae of the large tubes. From 

 Prasopora they are separated principally by the different form 

 and mode of growth of the corallum, by the amalgamation 

 of the walls of the tubes and their thickened character in 



