BRYOZOA. 237 



is most energetic, for the purpose of securing an abundant sujiply of 

 food, almost witliout exertion on the part of the creature itself. From 

 this most marked characteristic, Dr. Farre was induced to give them 

 the name of Oiliohrachiata. But it has since been discovered that 

 the Bryozoa possess a higher organisation than any of the preceding 

 families of zoophytes ; and also, from the presence of striped muscular 

 Jibre in their bodies, naturalists have transferred them, with other ani- 

 mals, the Fliostra, Lepralia, AnguirMria spatulata, Notamia, &c., to 

 the sub-kingdom MoUusoa. 



Bryozoa are generally found living together in great numbers, and 

 always clothed with hardy coverings or polypidoms. They subsist on ani- 

 mal bodies, and differ from most other mollusoa in being able to protrude 

 themselves from their cells. When th^ animals draw themselves within 

 their protective homes, to the bottom of which they are attached by a 

 sinewy ligament, they double themselves up by bending the lower part 

 of the body upwards. When the creature stretches forth, it presents a 

 beautiful sight, from its blossom-like appearance and busy cilia ; its 

 protrusion and retraction are performed with surprising quickness, as 

 it has two sets of muscles for the purpose, one acting on the body of 

 the animal, the other upon its cell. The oral extremity is surrounded 

 by a circle of long tubular tentacles covered with cilia ; at each of 

 these feelers or arms there is an aperture, the one at the base com- 

 municating with a canal that passes round the edge of the oral aper- 

 ture or mouth. The food passes down a long gullet, that contracts 

 during the process of swallowing. At the end of this is an orifice 

 that opens into what appears to-be a gizzard, having two bodies oppo- 

 site to each other, with a rough surface, as if for the comminution of 

 food, moved by muscular fibres. Those of the species without this 

 gizzard have a digestive stomach that secretes a coloured fluid. From 

 the upper part of the stomach near the entrance from the gizzard 

 arises an intestine, having a narrow opening surrounded by cilia that 

 proceeds upwards, ending in an orifice near to the tentacles, from 

 which the refuse food is ejected. 



" The connection of the polypidom with the soft portion of the 

 polyp is efiected," says Dr. Johnston, " by means of an inner tunic, 

 which, after enclosing the polyp's body as in a pouch, is afterwards re- 

 flected over the aperture of the cell, — the reflected portion becoming 

 exterior and solidified, either by calcareous depositions in its texture, 

 or by a mutation of its thin membranous character into a horny in- 

 vestment, better suited to the oflBce it has now to perform, of protect- 

 ing the sentient body from a too rough contact of the medium in which 



