188 ANTHOZOA HELIANTHOIDA. 



The Helianthoida are all animal feeders, and the principal 

 use of the tentacula seems to be to catch the errant prey and 

 convey it to the mouth. To disable the animal, and render 

 its struggles for escape unavailing, the class is furnished with 

 poison-vesicles and spicula similar to those which we have 

 already described as existing in the tentacula of the Hydra. 

 These organs were first discovered, I believe, by M. Quatre- 

 fages, but they have been described also by Wagner and 

 Erdl.* They are little elliptical capsules furnished with a 

 projecting spiculum, situated under the skin, sometimes scat- 

 tered over the whole body, and in other species confined appa- 

 rently to the tentacula, or even their tips, as in the genus 

 Corynactis. The poison secreted by them is very variable in 

 its power : in many species the sensation produced by hand' 

 ling them can scarcely be said to be unpleasant, but in others 

 it is smart and pungent. We must take our illustrations 

 from British species only.-f- I have often handled our com- 

 moner Actiniae without experiencing more than a slight heat 

 in the fingers, scarcely sufficient to draw attention ; but in 

 the Anthese, which have non-retractile tentacula, and in whom 

 the power of adduction is consequently weak, the activity of 

 the poison is heightened. In reference to Anthea cereus, 

 Rondeletius says, " Veritablement est Ortie, car si vous la 

 manies, elle pique fort." Rapp again says that the stinging 

 is only felt on places where the skin is thin, and scarcely in 

 the fingers, which is contrary to the experience of Mr. Cocks, 

 and of my friend Mr. Embleton, who has been stung with 

 Anthea Tuedise. Mr. Cocks further writes, " The fish that 

 has been so unfortunate as to be embraced by the tentacula of 

 the Anthea cereus, for a few minutes, loses its activity, be- 

 comes stupid, the eyes injected, and death soon closes the 

 scene. In August, 1845, I removed from the stomach of an 

 individual a partially digested fish, nearly' four inches in 

 length ; and I have frequently taken from the stomachs of 

 others, crabs two and a quarter inches in diameter." 



The native species, with the sole exception of Zoanthus, are 



* See the Microscopic Journal, ii. p. 73 ; and Reports on the Progress of Zoology 

 printed by the Ray Society (1845), p. 381. 



f For instances of urticating Corals, see Darwin's Voyages round the Worldy 

 p. 464. Duod. edit. 



