1 84 



POLYZOA. 



'CHAPTER XV. 



FIRST CLASS OF MOLLUSKS. 

 POLYZOA. * 



THOSE who have amused themselves with collecting sea- 

 weeds upon the shore, may have often observed their stems 

 to be covered in patches with a delicate film so thin as not to hide 

 the form of the surface on which it is spread, yet when closely 

 examined with a magnifying-glass discovered to consist of a vast 

 number of symmetrical cells, placed close to each other, some- 

 what like those of a honeycomb. Or the inquisitive collector may 

 have found a substance very similar to the above in its texture 

 and appearance, but floating loosely in the water, and itself taking 

 the form of a branched and leaf-like sea-weed, presenting on both 

 sides of its flattened expansion the same honeycomb arrangement 

 of tiny cells. 





: mim^m^m, 



FIG. 183. FLUSTRA FOLIACEA. 



Such are the Sea-Mats (Fins fro) (Fig. 183). If we take a portion of one 

 of these very common productions, and bring it under a lens of high magnify- 

 ing power, its entire surface is found to be made up on both sides by an assem- 

 blage of cells of a somewhat horny texture, the margins of which are beset 



* TroXiJs, polys, many ; $wa, zoa, animals ; so called because they are generally asso- 

 ciated in considerable numbers. 



