-^6 E. J. CHAPMAN ON THE 



Fam. 4. Halliidœ: — Septa distinctly twofold in their arrangement : 

 Hallia, E. & H. (including Aulacophyllum), Sil., Dev. 



§ 6. Vesiculosa. 



This section includes but cue family, that of the Cystiphyllidœ, distinguished by the 

 corallite cell being entirely filled with vesicular tissue. Eadiating septa absent or quite 

 rudimentary : 



Group A. — Aggregati : Septa absent or quite rudimentary. 



Cystiphylloides ( = aggregated forms of CysliphyUum, typified by C. aggre- 

 gatum, Billings), Dev. 



Group B. — Corniculati: Septa absent or rudimentary. 

 Cysliphylluvi, Lons., Sil., Dev. 



§ ï. Operculata. 



The forms of this section comprise a small number of peculiar types in which the 

 corallite cell is furnished with a cover or operculum composed either of a single valve or 

 of several valves. Eadiating septa are mostly rudimentary, but are well developed in 

 one genus. Provisionally, the representatives of the section may be classed in a single 

 family, with subdivisions as shown below : 



Fam Calceolidœ. 



Group A. — Anmdinacei : Corallum made up of cylindrical or reed-like corallites. 

 Septa rudimentary. 



Flelcheria, E. & H., Sil. 

 Rhizopora, de Kon., Carb. 



Group B. — Univalvati: Operculum composed of a single valve. Septa rudimentary. 



Calceola, Lam., Dev 

 Rhizophyllum, Linds., Sil. 



Group C. — Tetravalvati : Operculum composed of four valves. Septa well developed. 

 GoniophyUuni, E. & H., Sil. 



§ 8. Integri-Stellata. 



In the representatives of this section, the internal tabulae, so characteristic of palas- 

 ozoic corals generally, and the vesicular tissues which frequently accompany or replace 

 the tabulae, are practically unknown. Eadiated septa, on the other hand, are well deve- 

 loped. The known genera present collectively, two distinct types of configuration— a 

 disciform, and a coniform type, respectively. A central columella is present in some 

 representatives of the coniform type, and is absent in others. Hence the Inlegri-Slellala 

 admit of a separation into three well characterized families, as in the following dis- 

 tribution : 



