Alcvomdium. Z. ASCIDIOIDA. 303 



be distinct from ours, for a very careful examination has satisfied me 

 that the tentacula are 16 in number. 



D'Orbigny says that the Ulva diaphana of the Flore Fran9aise 

 " n'est autre chose qu'un amas de series d'ceufs d'une espece de gas- 

 teropode nu." Mem. du Museum, vi. 181. The description, how- 

 ever, so evidently belongs to the Alcyonidium before us, as to make 

 it almost certain that this remark has originated in some misapplica- 

 tion of it. 



2. A. HIRSUTUM, polypidom variously divided, compressed^ 

 the surface covered with minute conical papillce or polype-cells. 

 Fleming. 



Plate xlii. Fig. 1, 2. 



Alcyonium gelatinosum, Fabric. Faun. Groenl. 447 A. hirsutumt 



Flem. Brit. Anim. 517. Johnston in Zool. Joum. iv. 418. and in Trans. 

 Newc. Soc. ii. 231, pi. 9, fig. 1. L'A. vein, Blainv. Actinolog. 525. 



Uab. Parasitical on various sea-weeds, at low-water mark, very 

 common on the coasts of Scotland and North of England. Coast of 

 Devonshire, 3Ir Jos. Alder. 



Polypidom variously divided, often proliferous, sometimes sub-cy- 

 lindrical, commonly flattened and palmate, of a dirty straw-yellow 

 colour, often partially stained with red, and marked with numerous 

 yellowish circular spots irregularly disposed. It is thickish, some- 

 what cartilaginous, and to the naked eye resembles a compact sponge. 

 When viewed through a common magnifier, the surface is seen to be 

 covered with close-set conical transparent papillae, each of which is a 

 cell containing a polype with 16 long filiform tentacula, and in its 

 structure resembling the polype of a Flustra. The yellowish spots, 

 mentioned in the description, are produced by clusters of ova lying- 

 imbedded in the cellular texture. These are opaque milk-white, 

 large enough to be easily visible to the eye, of a roundish figure, 

 but not all of them alike, for some are ovate, and others incline 

 to a heart-shape, rather compressed, the surface uneven. The ^^g is 

 not clothed all over with cilia, but there is a fringe of cilia encircling 

 it ; these cilia appear to be of a yellowish colour, and to be hooked 

 near the apices, (wood-cut No. 7, page 51.) They are of equal size 

 and shape, and all inclined in one direction, moving with a uniformity 

 and quickness which is admirable and very pleasing to the beholder. 

 When the e^^ is at rest, their velocity is not diminished, excepting 

 at the will, so to speak, of the ovum, for it may be seen to become 

 slower and less constant, to cease entirely for a moment, and again 

 be renewed with its former force. The e^^ at rest will at once start 



