148 



FAMILY III.— ANTHEAD^E. 



In my " Synopsis of the British Actinise," (see Annals' 

 of Nat. Hist, for June 1858,) I had associated Anthea with 

 Actinia, in one family, distinguished by the negative 

 character of lacking suckers, warts, and loop-holes. But 

 groups founded on negative characters are always unsatis- 

 factory ; and maturer consideration has convinced me that 

 the positive diversities of these genera are of sufficient im- 

 portance to warrant their separation into distinct families. 



The members of the family Antheadce are marked by 

 a great development of the tentacular system. The tenta- 

 cles extend to a remarkable length, — in the typical genus 

 often reaching to twice or thrice the diameter of the disk, — 

 and are very flexuous. These organs have thinner walls 

 than usual, but are lined with a thick coat of comparatively 

 large pigment-grains of a deep brown hue. They show 

 a greater tendency to discharge the water which ordinarily 

 distends them, by contracting in diameter than in length, 

 the effect of which is, that these organs under irritation 

 collapse into a shrivelled or withered condition. 



Another remarkable peculiarity is the almost total in- 

 ability to retract the disk and tentacles, and to close over 

 them the margin of the column, — the common mode in 

 which Actinioi'ds seek protection from annoyance. It is 

 true that, on rare occasions, and when perfectly undisturbed, 

 I have seen both Anthea and Aiptasia in this retracted 

 condition ; but still, even then, there is a tenseness and 

 globularity in the covering column which is at once seen 



