SYNOPTICAL CLASSIFICATION. 17 



** A single layer of ceils. 



t Polyzoarium reticulate. 



40. Retepora. 



ft Polyzoarium entire. 



41. Hemesciiara. 



/S. Liberce. Polyzoarium unattached, usually discoid, conical or irregular. 

 Fam. 15. SELENARIIDuE. 

 * Vibracula inter-serial. 



42. LUNULITES. 



** Vibracula intra-serial. 



43. CUPULARIA. 



*** Vibracula scattered. 



44. Selenakia. 



(c) Cells disposed around an imaginary axis. 



Fam. 16. VINCULJRIID^. 



45. ViNCULARIA. 



Or in a tabular form, as follows, in which those families, genera, &c., in which fossii 

 species occur, are printed in italics : — 



