30 CELLULARIIDJG. 



The radical fibres are shown in Mr. Boswell's figure ; and 

 they are also present in Mr. Norman's fragment. They 

 originate at various points on the surface of the lower 

 cells. 



Family III. Cellulariid. 



CELLULARID^E, (part.) ( Johnston, Br. Zooph. 



CELLULARIAD^, Busk, B.M. Cat. 



CABEREAD^E, id. ibid. 



CELLULAHIE^E (part.), Smitt, Krit. Forteckn., (Efvers. Skand. Hafs-Brj-ozoer. 



ZocEciA in two or more series, closely united and ranged 

 in the same plane ; avicularia and vibracula, or avicu- 

 laria only, almost universally present, sessile. ZOA- 

 RIUM erect, dichotomously branched. 



IN this family the stems and branches which compose the 

 plant-like zoarium are formed of lines of cells placed side 

 by side in the same plane, and intimately united. The 

 structure is compact, and there is no tendency to the free 

 and lax habit of growth which characterizes the next 

 group (Bicellariid(B}. The cells are generally either sub- 

 oval above, and more or less produced and narrowed below, 

 or subquadrangular. The aperture, which is usually 

 armed with spines, and often protected by an opercular 

 plate (modified spine), is placed on the upper portion of the 

 front of the cell, and is for the most part directed straight 

 downwards. It is elliptical or oval in form, and usually 

 closed in entirely by a membrane ; but in a few cases it is 

 partially covered by a calcareous lamina. 



As a rule the various appendicular organs are deve- 

 loped abundantly in this group. The marginal spines 

 are often present in profusion, attaining a very large size, 

 and assuming (as amongst the Menipece) very fantastic 

 forms. 



