TUBULIPORA. 443 



Ceriopoea (part.), Hageuow. 

 PiiALANGELiA (sp.), Gray. 

 Obelia (sp.), Lamouroux. 

 Reptotubigera, D'Orbigiiy. 



Generic Character. — Zoarium adnate or decumbent 

 or suberect, forming a variously shaped expansion, either 

 entire, or lobate, or branched. Zocecia tubular, partially 

 free and ascending, arranged in divergent series. 



A COLONY of Tubulipora originates in the small discoid 

 body which constitutes the primary stage of most of the 

 Cyclostomata, From this a single cell is developed, and 

 from this a second, usually bent in the opposite direction ; 

 these are followed by an increasing number of series, 

 which diverge more or less on each side. In some cases a 

 simple flabellate crust is thus formed ; in others it divides 

 into lobes, which again subdivide. When the di\ision 

 and subdivision are carried to a great extent we have 

 beautifully radiated specimens, in which the lobulate 

 branches spread out circularly round the point of origin 

 (Plate LXI. fig. 4«). 



In certain forms the primary flabellate expansion 

 remains unbranched, or is simply bilobate, and as it 

 increases bends backwards on each side, and ultimately 

 incloses the primary disk, which becomes the centre of a 

 somewhat circular colony. On this mode of growth the 

 genus Phalangella of Gray is founded. 



The cells in Tubulipora are generally (but not univer- 

 sally) free for a very considerable portion of their length. 



I can see no sufficient ground for placing Tubulipora 

 and Diastopora in separate families ; the two genera are 

 nearly related and have many common characters. 



