FREE MESSMATES. 41 



Tlie Bryozoaria, the animal mosses, estaLlisli them- 

 selves on all solid bodies at the bottom of the sea, like 

 true mosses on stones or on trees. One species, a Mem- 

 hranijwraj is usually found on the common mussel. These 

 animals are of small size, group themselves in colonies 

 on the surface of shells and of polyparies, or even on 

 crustaceans, and form by their union a fine kind of lace, 

 the dazzling whiteness of -which often comes out sharply 

 on the varying and glittering colour of the shell. This 

 is because each animal lodges in a cell which is not 

 larger than the head of a pin, and all the cells of a colony 

 are grouped together with the symmetrical regularity of 

 the fa9ade of a Gothic building. 



Many Bryozoaria live in such a manner that it is- 

 impossible to say whether they are messmates, or have 

 installed themselves by chance in a hiding-place for 

 which they have no predilection. A charming bryo- 

 zoon is developed in abundance on the carapace and the 

 claws of the Arcturus Baffini, on the coast of Greenland, 

 and propagates itself with extreme rapidity. On a single 

 Arcturus we have found, scattered over its claws by the 

 side of each other, Balani, Spirorbes, SertulariEe, and 

 vasf colonies of Membranij)ora. One can see, merely by 

 this example, the great zoological riches of the polar seas. 



Certain annelids off the coasts of Normandy and 

 Brctagne are the abodes of a bryozoary known under 

 the name of Pedicellina, or Loxosoma. This interesting- 

 animal, which my fellow-labourer, Mons. Hesse, took 

 for a Trematode, and whose drawings had led me into 

 eiTor, lives like others at liberty while young, and soon 

 fixes itself to a Clymenian, in order to pass as a mess- 

 mate the later period of its life. We have called it 



