AND EXPLANATION OF TERMS. 3 



The warts (verrucce), in some species, are hollow, and 

 furnished with a muscular arrangement by which a vacuum 

 is formed, and the edges adhere firmly to foreign bodies ; 

 these may be called SUCKERS (acetabula). Other species 

 have the skin and the muscular beds beneath it pierced 

 with minute orifices, for the emission of armed threads ; 

 these may be called loop-holes (cinclides). 



3. The Disk (Fades). 



This is the flattened upper extremity of the column, as 

 the base is the flattened lower extremity. Its outline is 

 circular ; and this is recognised without difficulty when, as 

 is usually the case, the edge is plane (plana) ; but some- 

 times the edge is WAVY (undulata), as in bell is ; or even 

 deeply frilled (sinuosa), as in diantlius. In Actinia 

 proper, the disk bears, just within its margin, a row of 

 spherules (spkcerulce marginales) ; and, in every species, it 

 carries the tentacles, and is pierced at the centre by the 

 mouth. Converging lines (radii) cover the surface of the 

 disk, starting from each tentacle-foot and meeting around 

 the mouth. One RADIUS on each side of the disk, leading 

 to each MOUTH-ANGLE (gonidium) , is often more marked 

 than the rest ; these may be termed GONIDIAL radii (radii 

 gonidiales). 



4. The Tentacles (Tentacula). 



These are hollow cones springing from the surface of the 

 disk, and arranged in one or more series of circles towards 

 its margin. When there are more circles than one, that 

 circle which is nearest the centre may be called the first 

 ROW (series prima) ; that which stands next to it towards 

 the margin the SECOND (series secunda) ; and so on till we 

 reach the OUTERMOST (series extima). With respect to 

 each individual tentacle, its front (avtica) is that aspect 



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