ACTINIA. 203 



prominent external features, or the peculiarities of their nature, as the 

 type. But all these conditions should be well understood. 



The Actinia is very far removed from the Holothuria, with which 

 some authors nearly approximate it. Indeed, I have seen no correspon- 

 dence between them. 



§ 1. Actinia mesembryanthemum — Equina.* — Plates XLV., 

 XL VI., XL VII. — I took a specimen of this Actinia in August 1828, at 

 North Berwick, where the species is abundant, among the crevices of the 

 rocks and in the pools remaining still replenished after the recess of the 

 tide. It was originally very fine, though not of the largest size : and I 

 computed from comparison with those bred in my possession, that it must 

 have been then at least seven years old. During two months, as after- 

 wards, it continued in great vigour and of ample dimensions, being at that 

 time delineated. — Plate XLV. 



While considering such animals mature, we must allow that their 

 organization receives subsequent accessions, nor can I say at what period, 

 certainly a distant one, they cease to grow. 



Firmly affixed by the spreading base, the disc of this species ex- 

 panded above is begirt by a triple row of tentacula, each extending an 

 inch. Their number augments with age, and hence, at the latest period 

 of observation, they had here amounted to about 100, in twenty years. 

 The whole are unequally divided among the three rows ; the inner row 

 being composed of fewest, but they are the largest. 



At the external root of the tentacula of the outer row, there is a 

 number of apparently solid tubercles ; each, however, is pierced by an 

 orifice, which opens and dilates occasionally, some time after the animal 

 has fed. 



* I find it a vain attempt to reconcile the numerous synonyms abounding in different 

 authors, with the different species falling under my observation. The accurate resemblance 

 of the figures given here to the originals, will prove the reader's best guide. Naturalists 

 will find valuable auxiliaries in the works of Lamarck and Dr Johnston. But, greater con- 

 fidence may be reposed in those of the latter. 



