158 PROF. p. MARTIN DUNOAW'S REVISION OF THE 



direct fission of a single calicle forming two separate ones with 

 distinctly raised walls, or by the upgrowth of the synapticula at 

 differ en b parts of the calicle to form new walls, the resulting 

 centres often forming mseandroid series, until the development 

 of their own wall isolates them. Septa not at all confluent, 

 entire, those of adjoining calicles quite separated by the raised 

 walls. Columella absent or forming a very small styliform pro- 

 jection at the point of coalescence of the septa. Synapticula 

 distant, very unequally and irregularly developed, being gene- 

 rally rather thick interseptal outgrowths of the wall. 

 Distribution. — Recent. Fiji Islands. 



Genus Mtcedium, OJcen, LeJirh. der Natur., Zool. 1815 ; Milne- 

 Edwards Sf Jules Saime, Hist. Nat. des Oorall. vol. iii. p. 72 

 (1860), pi. D 12. fig. 2 ; PourtaUs, Beep-Sea Corals, p. 48. 



Colony frondiform. Calices well developed, circumscribed, 

 usually a central one surrounded by concentric series of others 

 inclined and submammiilate, projecting or flat. Columella 

 variable, papillary, compressed, tubercular, or absent. Septo- 

 costge long, continuous. Synapticula exist. Common under- 

 surface naked and variably costulate. 



Distribution. — Becent. Caribbean Sea, East-Indian seas, 

 Pacific. 



Eeuss noticed the genus in the Eocene, but probably the form 

 was a Thamnasfrcea. 



The variation in the species of this genus has been commented 

 upon by Pourtales, and it is evident that it is but slightly re- 

 moved from Lophoseris. 



Dana introduced the genus Phyllastrcea to include Mycedium 

 OJceni. 



Grenus Phtllastr^a, Dana, Zoophytes TJ. S. Escplor. Eccped. 

 1846, p. 40; see Sist. Nat. des Gorall. vol. iii. p. 75, 

 pi. D 12. fig. 1. 



Syn. Oxypora, Kent. 



Colony foliaceous ; polypes prominent and opening upward. 

 Coralla striated, scarcely echinulate. Costal striae coarse, unequal 

 and scabrous. Calicles large, margins projecting, and attached 

 laterally to the folia. Septa thin and spinulose. Columella 

 spongy. 



Distribution. — Becent. Amboyna, Pacific. 



