HALCYONELLEA : ALCYONIDIUM. 859 



Hah. Deep water, attached to old shells and stones. 



The polypidom is attached by a narrow base to the substance from 

 which it grows, and rises to the height of from six to twelve inches, 

 " sometimes attaining the length of two or three feet." It resembles a 

 compact sponge, but is more pellucid and gelatinous ; sometimes simple 

 and entire, usually branched, and in an irregular and multifarious 

 manner : the colour, as is well observed in " English Botany," varying 

 from a very pale brown, almost like that of wet sea-sand, to a clear 

 yellow ; in the latter case the polypidom has exactly the appearance 

 of barley-sugar of the paler kind. The surface is smooth and 

 speckled with minute dots produced by the dark bodies of the in- 

 habitant polypes, which protrude their tentacula through the angular 

 apertures, and are all placed immediately underneath the skin, for 

 the centre of the polypidom is a clear transparent jelly traversed 

 with corneous fibres, forming a very wide and irregular net-work. 

 The polypes are so intimately connected with their cells, that it is 

 almost impossible to remove them without mutilation. They have six- 

 teen filiform tentacula, disposed in a single circle, which are capable 

 of being retracted within the cell. " The tentacula are sixteen in 

 number, (occasionally fifteen,) fully two-thirds the length of the 

 body of the animal, and extremely slender and flexible. When ex- 

 panded they are frequently seen to roll up closely upon themselves, 

 even down to their base, the revolution taking place either inwardly 

 or outwardly, and in one or more arms at the same time. Their full 

 expansion afibrds a more perfect campanulate form than is usually 

 met with in this class, each of the arms having a slight curve out- 

 wards towards its extremity, which gives to the whole a very ele- 

 gant appearance. It is remarkable that in some specimens the arms 

 are much shorter on one side of the body than on the other." Farre. 



" The stomach is not furnished with a gizzard in this species. The 

 intestine forms a considerable elbow at its origin, and is short and 

 wide, terminating not as in other cases near the tentacular ring, but 

 about midway up the body, at a point opposite the base of the setae, 



" A very singular organ was frequently observed, consisting of a 

 little flask-shaped body situated between the base of two of the arms, 

 and attached to the tentacular ring by a short peduncle. The cavity 

 in its interior is lined with cilia which vibrate downwards towards 

 the outer, and upwards towards the inner side ; it has a narrow neck 

 and a wide mouth, around which a row of delicate cilia are constant- 

 ly playing. No flow of fluids could ever be detected through it, 

 nor did the use of carmine assist in showing with what parts the 



