243 



CHAPTEE XIY. 



First Class of 3Iollusca. 



POLYZOA.* 



Those who have amused themselves with collecting 

 seaweeVls 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-giass, discovered to consist of a 

 vast number of symmetrical cells, placed close to 

 each other, somewhat like those of a honeycomb. 

 Or the inquisitive collector may have found a sul^- 

 stance 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 expan- 

 sion the same honeycomb arrangement of tiny cells. 

 Such are the Sea-Mats (Flustra) (Fig. 183). If we 



/ 





Fig. 1S3.— Fi-rsTRA foliacka. 

 * iroAvs, polys, many : (a>a, zoa, animals, so called because they 

 are generally associated in considerable numbers, 



M 2 



