COEALS AND COEALLIFOEM TYPES. 47 



Fam. 1. CycHnidœ : — Coralhxm simple, disciform. 



(xroup A. — Sjdniferi: Septa represented by longitudinal rows of short spines. 



Acanthocychis, Dyb., Sil. 

 Group B. — Alternati: Septa, alternating in length, regularly arranged. 



Palœoct/clus, E. & H., Sil. 



G-roup C. — Su/cati: Cup with one or more septal furrows, towards which some of 

 the septa commonly incline. 



Microci/clus, Meek, Dev. 

 Campophi/Uum, E. & H., Dev. 

 BaryphyUum, E. & H., Dev. 

 Hadrophyllnm, E. & H., Dev. 



Fam. 2. Petraidœ : — Corallum simple, conical, straight or curved, without columella. 



Pelraia, Munst., Sil., Dev., Garb. 

 Polycœlia, King., Palœozoic. 

 Kenophyllum, Dyb., Sil. 



Fam. 3. Cyathaomnidœ : — Corallum coniform, simple, a central columella present. 



Cyathaxonia, Mich., Sil., Dev., Carb. 

 Duncanella, NichoL, Sil. 

 Duncania, de Kon., Carb. 



