i6 



TABULATE CORALS. 



general structure, that this genus must almost certainly be 

 placed alongside of the latter, even if not actually united with 

 it, as proposed by Professor Martin Duncan. We may thus 

 abolish the family Seriaioporida^, of which Seriatopora was the 

 type. The genus Pocillopora is Recent and Kainozoic, and it 

 is questionable if any fossil forms of Seriatopora are known. 

 It may at any rate be taken as certain that the alleged forms 

 of Seriatopora from the Palaeozoic deposits will be proved to 

 have different affinities. The Palaeozoic genera Trachypora, 

 Dendropora, and RJiabdopora, usually associated with Seria- 

 topora, Lam., are, again, truly Perforate Corals destitute of a 

 coenenchyma, and belonging to the Favositidcs. 



III. Favositid/E. — The corallum in this family is of very 

 variable form, but is composed of polygonal or subcylindrical 

 corallites, which are usually in close contact throughout their 

 entire extent, and are furnished with well -developed walls. 

 The walls are, however, perforated by a greater or smaller 

 number of rounded apertures — the " mural pores " (fig. 4, b) 

 — by which the visceral chambers of contiguous polypes are 

 placed in direct communication. There is no true ccenen- 

 chyma ; and the condition of the septa is extremely variable, 



Fig- 4-— A, Portion of the corallum a{ Favosites favosa, of the natural size ; B, Portion of four 

 corallites of Favosites Gothlandica, enlarged, showing the tabula: and the " mural pores." 



these structures being sometimes obsolete (some forms of 

 Trachypoi^a, &c.), sometimes in the form of marginal lamellae 

 or ridges {Nyctopora, Nich.), and most commonly represented 

 by vertically-disposed rows of spinules (most species of Favo- 



