CLASS POLYZOA. 



257 



gives birth to an individual which, by budding, produces 

 long chains of aggregated individuals* greatly different 

 from the parent. Each of these produces an egg, which 

 hatches an individual like the grandparent. Thus the 

 series is repeated endlessly. 



CLASS VI. POLYZOA. 



General Characteristics. The Polyzoans **ff- us - 

 (many-animals), or Bryozoans (moss-animals), 

 are compound ; each individual, however, in- 

 habiting a separate cell or tube. The mouth is 

 surrounded with ciliated tentacles, and the 

 whole animal can usually be entirely withdrawn 

 into the cell, which is in some species soft and 

 flexible, in others horny, and in others calca- 

 reous. In the genus BowerbanJcia, the struc- 

 ture is so delicate and transparent that the 

 interior may be clearly seen. The Bryozoan is 

 thus perceived to have a complex digestive ap- 

 paratus floating freely in the general cavity a 

 gizzard for triturating the food, a liver for 

 secreting bile, an intestinal tube, and a distinct 

 excretory orifice outside the circle of tentacles. 



The Flustrae, or " Sea-mats," are Bryozoan 

 communities, consisting of a multitude of 

 horny, calcareous cells, some species incrusting 

 stones, others 'spread out like a thin net-work 

 of gauze, each cell containing an individual polyzoan. The 

 whole progeny of a single isolated specimen of sea-mat spring, 

 by budding, from an embryo produced in each egg, within 

 which two little Bryozoa are found. These make their 



Bowerbankia. 

 a. (Esophagus; 



b. Gizzard; 



c. Stomach ; 



* The progeny of a single egg unite by the adhesion of their surfaces, or of little 

 suckers, so as to string out as far as the eye can reach. Being phosphorescent in the 

 night, these long-drawn bands give the effect of ribbons of fire, twisting and doubling! 

 as they rise and fall with the waves. 



