No. 2.] DEVELOPMENT OF MARINE ANNELIDS. 



259 



young trochophores, atrophies when the body begins to elongate, 



and a few clumps of short cilia appear upon the umbrellar surface. 



Two or three large slowly moving fiagella are found in front 





JRetC" 



' bay- 



Vein 



Pig. XIV. — Amfhitrite, 44 hours, dorsal; 

 gl.l., duct of left dorsal umbrellar mucous 

 gland; gl.r.., right dorsal umbrellar mucous 

 gland ; proh., problematic bodies , gl., ven- 

 tral umbrellar mucous gland ; imic, ventral 

 subumbrellar mucous gland ; j^.,seta; par., 

 paratroch ; czr., anal cirrus ; /, //, ///, ist, 

 2d, and 3d trunk segments. 



Fig. XV. — Amphitrite , 44 hours, right 

 side ; ap.tfi., apical tuft ; gl., and op.gl., 

 ventral umbrellar mucous gland and its 

 external opening; gl.r., right dorsal 

 umbrellar mucous gland; prob., prob- 

 lematic bodies; viuc, subumbrellar 

 mucous gland; v.c, ventral band of 

 cilia; par., paratroch; dr., anal cirrus. 



of the prototroch in the mid-ventral line. A ventral band of 

 short cilia connects the prototroch and paratroch, and a few 

 ciliary tufts and a large cirrus occur in the region behind the 

 paratroch (text Figs. X-XVIII). 



Setce, parapodia, etc. — When the larva has elongated and 

 has begun to divide up into metameres, it develops in each 



