122 ZOOPHYTES. 



FAMILY I. ACTINID^E. 



Astrceacea non coralligena, simplicissima, scepius basi affixa. 

 Non-coralligenous Astraeacea, not budding, usually attached at base. 



The appearance, general characters, and habits of the Actinia have 

 been already considered, and little remains to be added here, except to 

 mention some of the varieties of structure, and the groupings or 

 genera in consequence adopted. The most common form is that of a 

 cylindrical animal, with a coronet of simple slender tentacles en- 

 circling the mouth. The base, by which it attaches itself, is often 

 much spreading, and the same is also true of the upper extremity or 

 disk. The margin of the disk is very undulating in some species, 

 or appears as if gathered into a few large folds ; and that of the base 

 is either entire, undulating, gash-lobed, or edged by shallow crena- 

 tures. The tentacles may be much longer than the body, or rudi- 

 mentary, in a dense circle, fringing the disk, or scattered over its 

 whole surface, either equal or very unequal, with sometimes the 

 inner and sometimes the outer series much the longest : and in shape, 

 they may be terete and pointed (subulate), the usual shape, or 

 they may terminate in an obtuse point, or even rounded head. The 

 exterior surface is either smooth, granulous, lined with striae or 

 simply with coloured markings, papillose, tuberculate, or covered 

 with small suckers (suctorial vesicles), like those of the cuttle-fish : 

 and often the margin of the disk is edged with a series of rather 

 prominent tubercles, which seem to be rudimentary tentacles, or may 

 at least correspond to these organs. Though usually in several 

 series, there are a few species described, in which the tentacles 

 appear to be in a single series. The tubercles of the surface are 

 sometimes distinctly perforated ; but this perforate character is not 

 confined to the tuberculate species. 



From this, the common variety, there is a passage to others, in 

 which the tentacles are subdivided, branched, or papillose, or fur- 

 nished with suctorial vesicles, and these sucker cups sometimes cover 

 the surface of the disk. In some species, which bury themselves in 

 the sand, and thus prevent the aeration of the body through the sides, 

 one or more series of tentacles are often delicately lobed and frosted 

 with mossy projections or papillae, thus spreading a larger surface 



