Development of the Nemerteans. In the development 

 of these worms we are reminded of the mode of grow 

 Echinoderms, while in others the larvae attain the adult 

 by gradual development. In no order of animals, p< 

 there a greater range of variation in the mode of de\ 

 than in these curious worms. 



The simplest mode of growth is that described by Die 

 phalothrix, where the ciliated larva, after passing through 

 and planula 1 stage (being a two-layered sac, but not a 

 leaves the egg and undergoes no metamorphosis, the yoi 

 having no body cavity. In the Nemertes larva of Desc 

 a body cavity, but the larva is still an infusorian-like 1. 

 attains maturity by direct growth. Another Nemertean 

 munis) has been found by Barrois to have a somewhat n 

 plicated mode of growth than in the larva of Desor. 

 stages of development are like Fig.no. 

 those of the larva of Desor, the 



teans in which there is a very 

 complicated metamorphosis. J. 

 Miiller had described an animal vimh 

 caught with the towing net which he 

 had suspected that a Nemertes came f 



