ANTIIEAD^. 
149 
to be peculiar, and which suggests the notion that the 
effect is produced more by the distension of the column 
than by the contraction of the disk. In these cases, too, 
the slightest touch (which, in a Sagartia or Actinia^ under 
similar circumstances, would only cause a closer contrac- 
tion) is followed by the instant recession of the column, 
and the protrusion of the tentacles. 
The whole body manifests comparatively little contrac- 
tility. The shrinking of the parts from every touch, which 
in the Bunodidce and the Bagartiadce, is so excessive, going 
on even after decomposition has set in, and which is so 
annoying and so baffling to the anatomist, prevails to a 
far less degree in the Antlieadce ; and hence the family 
presents favourable conditions for dissection. The power 
of discharging mucus is also comparatively small. 
Though ordinarily adherent by the base, the power of 
adhesion is unwontedly feeble in the family ; the animals 
can be detached with the slightest force, and often spon- 
taneously free themselves. Both of our British genera 
have the habit of frequently crawling to the brim of the 
water, and then expanding their base upon the surface 
and allowing it to dry, floating by means of it with the 
body inverted, and the tentacles expanded in mid-water. 
An attentive observer sees in the habits of the Antlieadcc, 
and particularly in the lively and flexuous movements of 
the tentacles, an indication of superior muscular power in 
these organs, and also a higher degree of intelligence, or 
at least of perceptive faculty, than the Sagartiadee possess. 
Besides our own two genera, Aiptasia and Anthea, 
one or two exotic genera must belong to the family. 
If Mr. Dana has eorrectly described the Act. Jlagellifera of 
]\Iadeira, it must be generically distinct, notwithstanding its 
very close resemblance in figure and colour to the green 
variety of Anthea cereus. lie speaks of the inner row ot 
