MOLLUSCA. 



193 



removed to this type. The cells of a group are not con- 

 nected with a common tube, as in Caelenterates, and each 

 animal possesses a 

 distinct alimentary 

 canal and nervous 

 system. Sometimes 

 the colonies are foli- 

 aceous, or leaf-like, 

 as the Sea Mat, 

 Flustra, (Fig. 92,) 

 and at others plant- 

 like, as the Phimat- FlG 92 ._ SeaMati (Flustra /oliacea.) A. Magnified. 



ella. (Fig. 93.) They B - Natural size - 



sometimes spread over rocks and sea-weeds like delicate 



lace-work, and the majority are coral-making animals, or 



FlG. 93. Plumatella. a. Natural size. b. A group enlarged, c. Anal orifice. 



secrete carbonate of lime. The mouth of each animal is 

 surrounded by ciliated tentacles which serve for prehen- 



