FIRST ORDER OF ANNELIDA. 



THE TUBICOL.^*. 



Some form a calcareous homogeneous tube, resulting probably 

 from their transudation, like the shell of the mollusca, to which, 

 however, they do not adhere by muscles. Others construct it 

 by agglutinating grains of sand, fragments of shells, and par- 

 ticles of mud, by means of a membrane, which is doubtless 

 also transuded. There are some, in fine, whose tube is almost 

 entirely membranous, or homy. To the first of these belong, 



Serpula, Lin., 



Whose calcareous tubes cover, by twisting round them, stones, 

 shells, and all submarines bodies. The section of these tubes 

 is sometimes round, and sometimes angular, according to the 

 species. 



The body of the animal is composed of a great number of 

 segments. Its anterior part is spread into a disc, armed on 

 each side with several parcels of coarse hairs, and on each 



* M. Savigny, joining the ArenicolcB to this order, changes the name 

 into SerpulacecB. M. de Lamarck, adopting the same arrangement, 

 changes the name Serpulacea into Sedentaria. My genera of Tubicolce are 

 M. Savigny's family of Ampkitrite. With M. de Lamarck, they compose 

 those of Amphitritea and Serpulacea. With them, M. de Blainville forms 

 his order of Entomozoa chetopoda heterocrisina ; but contrary to his own 

 definition he has introduced there Spio and Polydorus. 



