CHARACTERS OF FAMILIES, ETC. XI 



Group ASTRANGI ACE.^ . 



Corallum increasing by the development of buds on stolons, 

 or on membraniform basal expansions. The corallites not united 

 by their sides, excepting accidentally by means o£ their walls, 

 and remaining short. Septa feebly denticulated. Dissepiments 

 almost rudimentary. 



Section — Madreporaria perforata. 

 Corallum composed essentially of porous sclerenchyma ; with 

 the septal apparatus well characterized, and consisting of six 

 primitive elements, but being sometimes represented only by 

 series of trabicuke. Dissepiments rudimentary ; no tabulae. 



Family — Madreporide . 



Corallum composite, increasing by gemmation. Ccenen- 

 chyma abundant, spongy and reticulate. Walls very spongy, 

 and not distinct from the coenenchyma. Septa lamellose, and 

 well developed ; loculi free. 



Family STYLASTERIDyE. 



Skeleton branched, calcareous, studded at intervals with cup- 

 like depressions, each of which exhibits a central chamber, occu- 

 pied axially by a styliform rod, and surrounded by a series of 

 secondary chambers, separated from one another by short septa. 



SUB-KINaDOM— MOLLUSCA. 

 Class — Bryozoa. 

 Alimentary canal suspended in a double-walled sac, capable 

 of being partially protruded. Mouth surrounded by a circle of 

 hollow, ciliated tentacles. Animals always composite. 



Order — Gymnol^emata. 

 Lophophore orbicular, or nearly so ; no epistome . 



Sub-order — Cyclostomata. 



Cells tubular. Mouth of the same diameter as the cell, with- 

 out any movable lip. 



Family — Sparsid^. 



Polyzoarium erect, simple or branched ; branches cylindrical, 

 or sub-compressed ; free or anastomosing. 



