164 Volcanoes. 



Actinia Tuediae is amongst the largest of our species. The 

 body, when relaxed, generally measures 3 in. in length, and 

 about the same in diameter ; it is of a uniform reddish or 

 brownish-orange colour, and either smooth or contracted at 

 pleasure into circular folds. The base is smooth and orange- 

 coloured, with a thin areolar skin. The mouth is ever vary- 

 ing in size and form ; and there are often protruded from it 

 yesicular-like lobes of a reddish colour, scored with fainter 

 lines. When fully expanded, the oral disk is not less than 

 4 in. across ; there is a smooth space between the mouth and 

 tentacula, which are very numerous, and placed in several 

 rows around the circumference ; those of the inner row are 

 larger than the others, measuring frequently 2 in. in length, 

 and they become gradually smaller in the exterior series. 

 They are of a chestnut or reddish flesh colour, often darker- 

 coloured towards the bases, but never variegated with rings 

 of different hues; thick and clumsy, tapered to an obtuse 

 point, marked longitudinally with distinct lines or impressed 

 striae, tubular, perforated at the ends, and constricted at their 

 insertions. The creature has no power of withdrawing them 

 within the oral aperture, as the greater number of Actiniae 

 have ; nor does it seem capable even of shortening them in 

 any considerable degree, but it twists them in a wreathed or 

 spiral form, or gives the whole circle a greater or less degree 

 of expansion. 



The trivial name which I have bestowed on this species is 

 intended to indicate the place of its first discoveiy, Tuedra 

 being, according to Sir Robert Sibbald, the ancient name of 

 the maritime parts of Berwickshire. It is not uncommon on 

 this coast, but is found only in deep water, whence it is drag- 

 ged up by our fishermen. I have often found the tentacula, 

 in a separate state, adhering to their lines; and as these retain 

 their irritability and motion for a long time, they are apt to 

 be mistaken for independent and perfect worms, which they 

 much resemble. Our figure represents the animal about one 

 half of its natural size. I am, Sir, yours, &e. 



George Johnston, M.D» 

 Berwick upon Tweedy Jan, 7. 1832, 



Art. XI. Volcanoes, By W. M. HiGorNS, Escj. F.G,S., and 

 J. W. Draper, Esq. 



From the similarity which is observed between inorganic 

 objects in all countries, it may be supposed that there is less 

 value in the detail of observations relating to them than in 



