TABULATA. 



199 



to the Alcyonaria the great group of extinct " Tabulate 

 Corals " of which Heliolites is the type. Lastly, Millepora, 

 as originally affirmed by Agassiz, has been shown to be like- 

 wise not a Zoantharian, but to be referable to the Hydrozoa. 



In spite of these great deductions, there still remain some 

 extinct groups of corals which may, in the meanwhile, be 

 retained to form the section Tabulata, though their true 

 affinities and systematic position are matters of great 

 doubt. 



1. Favositidce. The first of these groups comprises the 

 well-known " honeycomb " corals, and is almost exclusively 

 Palaeozoic in its range. In all the members of this family 

 the corallum is compound, the septa are rudimentary or 

 absent, the tabulae are extremely well developed, and 

 the walls of the corallites are perforated more or less freely 

 with apertures or "mural pores" (fig. 72). In their per- 

 forated walls and general structure the Favositidce make 

 such a near approach to such living genera as Alve-opora and 



Fig. 85. Portion of a mass of Favosites 

 ( iothlandica, of the natural size. Upper 

 Silurian and Devonian of Europe and 

 America. (Original.) 



Fig. 86. Fragment of Parasites (Emmon- 

 sia) Tiemispherica, of the natural size. Up- 

 per Silurian and Devonian of America. 

 (After Billings.) 



Favositipora, that it seems certain that they will ultimately 

 be removed from the "Tabulata'' and will be placed in the 

 Zoantharia Perforata, in or near the family of the Pori- 

 tidce. 



The type-genus of this family is Favosites itself, with 

 many species in the Silurian, Devonian, and Carboniferous 

 rocks. The corallum in this genus is massive or branched, 

 composed of more or less prismatic, closely approximated 



