CYATHOPHYLLOIDEA. 



29I 



become united to one another by the confluence of the outer ends of the 

 septa (fig. 160). The septa are "carinate," and alternately long and 

 short, a distinct fossula being usually present, and the symmetry thus 

 becoming clearly bilateral. The species of Pkillipsastrcea are prin- 

 cipally Devonian, but the range of the genus extends into the Carbon- 

 iferous period. 



Family 3. Clisiophyllidaz. — The corals of this family agree with 

 the Cyathophyllidce and Heliophyllidcz in the general character of 

 possessing a well-marked exterior vesicular zone and a central tabu- 

 late area. The central tabulate area is, however, traversed in this 

 family by an extensively developed and complex spurious columella, 

 formed partly of vertical, often twisted plates which have a general 

 radial direction, and partly of vesicular tabulae which intersect the 

 former in an obliquely ascending direction. This massive pseudo- 

 columella appears in the floor of the calice as a rounded or conical 

 boss of greater or. less size, the surface of which, in well-preserved 

 specimens, shows radiating, often spiral ridges. The septa are 

 numerous, of two sizes, alternately equal. The symmetry is usually 

 markedly bilateral, a well-developed " fossula," lodging the " cardinal 



Fig. 170. — Morphology of the Clisiophyllidce. a, Transverse section of Dibunophy llutn sp., 

 from the Carboniferous rocks of the North of England, slightly enlarged ; b, Longitudinal 

 section of the same, h, " Cardinal septum " situated in the " fossula " ; g, " Counter septum " ; 

 e, Outer zone of vesicular dissepiments; t, Central area of anastomosing tabulae; c, The 

 columellar plate. (Original.) 



septum," being present. The " cardinal septum " is shorter than the 

 other long septa, and the " counter septum " is often specially devel- 

 oped. The septa are thickened by lateral deposits of stereoplasma, 

 and are not " carinate." The corallum may be simple or composite. 

 The Clisiophyllid(z are mainly, if not exclusively, confined to the 



Milne-Edwards and Haime state that a columella is present, but no traces of this 

 structure appear in thin sections. 



