42 E. J. CHAPMAN ON THE 



Aulopora, Groldf., Sil., Dev., Carb. 

 Reptella, Eolle, Sil., Dev. 

 Cladoconus, McCoy, Carb. 



§ 2. Tabulata. 



The corals of this section are distinguished by the presence of numerous transverse 

 tabulae in their component cells, coupled with the absence of radiating septa, or the rudi- 

 mentary, imperfect character of these when indistinctly present. They have been 

 separated widely in many systems, and have been allotted partly to the Alcyonaria, partly 

 to the Bri/ozoa, and in part also to the Rugosa generally. Whilst thus manifestly occupy- 

 ing an uncertain position, the two fundamental characters given above — namely, the 

 presence of tabulœ, with absence or merely indications of septa — are sufficiently definite 

 to warrant their retention in a common group, and to show at the same time their 

 relations to the coral forms of section .3, in which both tabulœ and well developed septa 

 are present. The more typical representatives, including all the better known genera, 

 may be arranged under six families, as in the following synopsis : 



Fam. 1. Cliœletidce : — No cœnenchyme Corallites, capilliform, or of small diameter. 



Chœteles, Fisch. (including Monliculipom and Stenopora), Lr. 



Sil. to Trias. 

 Teiradium, Safford, Lr. Sil. 



Fam. 2. Beaumontidœ : — No cœnenchyme. Corallites comparatively large, polygonal, 

 with imperforate walls. 



Beaumontia, E. & H., Carb. 



Fam. 3. Favositidœ: — No cœnenchyme. Corallites, polygonal, round or crescented at 

 surface, with perforated walls. 



G-roup A. Plani. — Tabulée horizontal or inclined : 



Favosites, Lmk., Sil., Dev., Carb. 

 Columnipora, Nich., Lr., Sil. 

 Alveolites, Lmk., Sil., Dev. 

 Pachypora, Linds., Sil. 

 Nodulipm'a, Linds., Sil. 



G-roup B. Tumidi. — Tabulae convex or more or less vesicular : 



Emmonsia, E. & H., Sil., Dev., Carb. 

 Michelinia, de Kon., Dev., Carb. 



Fam. 4. Halysitidœ : — Corallites tubular, imperforate, connected only at opposite 

 sides, typically in chain-like aggregations. Tabulœ, horizontal : 



Halysites, Fisch., Sil, 

 Tliecostegites, E. & H., Dev. 



