CHAP. XV 



Backboneless Animals 



233 



usually very different from the adults — little barrel-shaped or pear- 

 shaped ciliated creatures known as Trochospheres. 



Some of the Chsetopods multiply not only sexually, but asexually 

 by dividing into two or by giving off buds from various parts of 

 their body. Strange branching growths, which eventually separate 

 into individuals, are well illustrated by the freshwater Nais, and 



Fig. 43. — A budding marine worm {SylUs ramosa). From Evolution of Sex ; 

 after M'Intosh's Challenger Report.) 



Still better by a marine worm, Syllis ramosa, which almost forms 

 a network. 



Many sea-worms have much beauty, which some of their names, 

 such as Nereis, Aphrodite, Alciope, suggest, and which is said to 

 have induced a specialist to call his seven daughters after them. 



Along with the Chaetopods, we include some other forms too 

 unfamiliar to find more than mention here, the Myzostomata which 

 form gall-like growths on the feather-stars which they infest, the 

 strange Bonellia in which the microscopic male lives as a parasite 

 within the female, and some very simple forms which are sometimes 

 called Archi-Annelids. 



