ACTINIADjE: ACTINIA. 235 



perceptible movement,* as is their usual method ; or by reversing 

 the body and using the tentacula for the purpose of feet, as Reaumur 

 asserts,t and as I have once witnessed ; or lastly, inflating the body 

 with water to render it more buoyant, they detach themselves and 

 are driven to a distance by the random motion of the waves.^ They 

 feed on shrimps, small crabs, whelks, and similar shelled mollusca, 

 or, probably with indifference, on whatever animals are brought 

 within their reach, and whose strength or agility is insufficient to 

 extricate them from the grasp of their numerous tentacula ; for as 

 these organs can be inflected in any direction and greatly length- 

 ened, they are capable of being applied to every point, and adhere 

 by suction with considerable tenacity. The food is retained in the 

 stomach for ten or twelve hours, when the undigested remains are 

 regurgitated, enveloped in a glairy fluid, not unlike the white of an 

 egg. The size of the prey is frequently in unseemly disproportion 

 to the preyer,|| being often equal in bulk to itself. I had once 

 brought me a specimen of Act. crassicornis, that might have been 

 originally two inches in diameter, and that had somehow contrived 

 to swallow a valve of Pecten maximus of the size of an ordinary 

 saucer. The shell, fixed within the stomach, was so placed as to 

 divide it completely into two halves, so that the body, stretched 

 tensely over, had become thin and flattened like a pancake. All 

 communication between the inferior portion of the stomach and the 



* Reaumur found that they require an hour to advance one or two inches ; but I 

 have seen A. mesembryanthemum advance at a rate considerably quicker half an 

 inch in about five minutes. 



f Mem. de 1'Acad. Roy. des. Sc. 1710, p. 621. 



J " An Actinia, in my possession, walked up the sides of a glass, by alternately 

 adhering with its disc and base in the Leech-fashion. I observed that a Mediter- 

 ranean Actinia, which is habitually free, swims by contractions, in the manner of a 

 Medusa. When confined in a glass, it attached itself to the sides by its base, just 

 like a shore-actinia." Professor Edw. Forbes. 



According to Gaertner, the animal fixes the tentacula by throwing out of their 

 whole surface " a number of extremely minute suckers, which, sticking fast to the 

 small protuberances of the skin, produce the sensation of a roughness, which is so far 

 from being painful, that it even cannot be called disagreeable." Phil. Trans, v. 52, 

 p. 76. No such structure can be discovered. 



|| " Fauces haec animalia, subtus sacci instar penitus clausa, superne habent pro 

 libitu tarn patulas, ut mytulos satis magnos aliasve conchas ingurgitent, e quibus, 

 modo nos fugiente, pisces extrahere, et evacuatas testas per eandem aperturam, ejicere 

 rursus valent. Quse testae, si majores sint, et segre per fauces transituras essent, 

 Priapus non solum fauces late expandit, sed easdem, ut solemus tibialia, quasi 

 invertit, quo spntium brevius et apertura fit latior." Basteri Opusc. Subsec. i. lib. iii. 

 122. 



