METAZOA COELENTERA. 139 



MADREPORAKIA FUNGIDAE. 



Palaeocyclus (No. 237) and Cyclolites (No. 237) are 

 mushroom-corals which antedate our present Fungia. 

 From a study of the early stages of the latter, however, 

 it is probable that all these coral animals arose from a 

 cup-shaped rather than a mushroom-shaped ancestor. It 

 may be that a still more remote ancestor was disc-shaped, 

 as we have already said, and that the Madreporaria 

 Fungidae, which possess a similar plate-like form, are its 

 specialized and reduced descendants. 



Nothing is known of the young stages of Palaeocyclus 

 and Cyclolites. The adult is disc-shaped and the epitheca 

 is confined to the base. The septa rise as so many walls 

 of varying length from the basal plates. 



Turning to the development of Fungia we find that the 

 parent stock is attached (PI. 239, fig. i). It is cup-shaped 

 with a distinct theca, while the cavity of the cup is divided 

 into chambers by septa. In this stage it resembles Caryo- 

 phyllia. In time the oral disc increases in size at the 

 expense apparently of the thecal portion (fig. 2). The 

 growth is lateral, until at last the young Fungia separates 

 from the parent stock a short distance below the disc 

 where the dark line is seen in fig. 3. When set free the 

 Fungia has an opening beneath, where it was fastened, 

 but this quickly fills up by a secretion of carbonate of 

 lime. The scar is seen in young specimens (No. 240). 

 The Fungia is henceforth free (PI. 239, figs. 4, 5) with 

 only slight evidences on the lower side of its attachment, 

 and these finally disappear (fig. 6) . The parent stock 

 continues to bud forth other animals which likewise become 

 detached. According to Semper 1 the parent stock is 

 comparable to the strobila of the Discophora and exhibits 

 a true alternation of generations. 



1 Zeitschr. f. wiss. Zool., XXII, 1872, p. 267. 



