No. 424.] THE GENUS TRYPANOSVYLLIS. 315 
lengthy chain would be exposed, particularly if very slender 
and attached to a stock of vastly greater bulk and strength, 
is evident. 
The absence of organs of nutrition, the collateral mode of 
origin, and the fact that the smaller and simpler members of 
the genus still produce stolons point unmistakably to the high 
degree of specialization attained by the sexual zooids of these 
two species of Tryp yllis. Both in their structure and in 
their mode of development they unquestionably represent the 
most specialized mode of asexual reproduction, not only among 
the Syllidae, but among all known annelids. 

