SSCHARID^. 



521 



and which are also very distinct in the Notamia ; but 

 which, in the present instance, would seem to have for 

 their chief function the drawing-up or corrugation of the 

 membraneous portion of the polype-cell. These muscular 

 fibres have a distinct central nucleus or thicker portion, as 

 is the case in the analogous muscles in some other polypes. 



EscHARiDiE. — This interesting family justly deserves the 

 great attention many naturalists have bestowed upon it. 

 Linnaeus named it Fliistra, from the 

 Saxon word Jlustran, to weave ; it is 

 commonly called a Seamat, and re- 

 sembles fine network spread over 

 stones, rocks, shells, and marine plants. 

 This network, when submitted to the 

 powers of the microscope, is found to 

 be a cluster of cells, in each of which 

 dvveils an animal, that protrudes its 

 feelers when searching for food, and 

 sinks into its little home when tired, 

 or alarmed by approaching danger. 



Dr. Grant estimates that a single 

 Flustra has as manv as four hundred 

 millions of cilia on these restless ten- 

 tacles. The tentacula vary from ten to 

 twelve ; the general organization con- 

 sists of a guUet, a gizzard, a stomach, 

 and intestines, the body itself being quite transparent. 

 When collected together in clusters they take the form of' 

 a delicate minute tree, having cells in all parts, and of 

 various colours. Lamouroux says : " When the animal 

 has acquired its full growth, it protrudes from the opening 

 of its cell a small globular body, which it fixes near the 

 aperture, and, as it increases in size, soon assumes the form 

 of a new cell; it is yet closed, but through the trans- 

 parent membrane that covers its surface the motions of 

 a polype may be detected ; the habitation at length 

 bursts, and the tentacles protrude ; eddies are pro- 

 duced in the w^ater, and conduct to the polype the 

 atoms necessary for its subsistence. The aperture of 

 the cells is formed by a semicircular lid, convex ex- 

 ternally and concave internally, which folds down wlien 



Fig. 245. — Eschara cer- 

 vicornis, Sea-moss po- 

 lype; the animal is 

 represented out of its 

 polypidom. 



