SYNOPSES OF NORTH-AMERICAN 
INVERTEBRATES. 
XIII. THE ACTINIARIA. 
G. H. PARKER. 
Tue Actiniaria, or sea anemones, are marine animals inhabit- 
ing the shallow and deeper waters of our coasts, and usually 
found attached to some rock or other firm object. They have 
been justly noted for their exquisite colors and forms. Asa 
rule, each species is represented by separate individuals or polyps, 
but in the Zoantheze (Fig. 22) colonies are formed by budding, 
much as in many corals. The sea anemones are further char-. 
acterized by the fact that they produce no independent skeleton 
and that their tentacles are very usually simple or undivided. 
In the more typical species the polyp has the form of a short 
cylinder, the attached end of which is known as the pedal disk, 
the free end the oral disk, and the intermediate part the 
column. 
The pedal disk is the organ of attachment for those species 
that are fixed and the chief organ for locomotion for those that 
move. It is usually well developed, but in species inhabiting 
muddy or sandy bottoms it is either reduced, as in Ammophi- 
lactis (Fig. 12), or entirely absent, as in the Edwardsice (Fig. 1) 
and the Ceriantheze (Fig. 21). 
The column is generally undivided, but in Halcampa (Fig. 3) 
as many as three parts can be distinguished: a pedal physa of 
small extent, an intermediate scapus corresponding to the col- 
umn in the restricted sense, and an oral capitulum, which often 
Suffers involution when the polyp contracts. The surface of 
the column is either smooth or more or less covered with emi- 
nences, known as ¢wbercles (Figs. 9, 10). In the Sagartinee (Fig. 
17) the column wall is very usually pierced by pores, cinclides, 
through which water from the internal cavity of animal and 
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