6. 
POLYCHAT LARV. 
Two pairs of transparent conical 
cephalic tentacles present at 
the anterior end of the 
prostomium; neurotroch, and 
T-shaped akrotroch with 
“hook” of cilia present at 
first; (‘Trochophore charac- 
terised by its great con- 
tractility, and by the above 
form of the akrotroch) : 
Parapodia uniramous; rami 
long except in very early 
stage; each with compound 
setae and at least one simple 
smooth seta (in many Syllds 
this last distinction would 
almost certainly not apply): 
(species distinguished by their 
setae, see Pl. I., figs. 2-4.) 
Dorsal and ventral rami of 
parapodia very short, with 
smooth and frilled capillary 
setae ; body somewhat 
elongated : 
Three pairs of tentacular cirri; 
larva rather small: 
Four pairs of tentacular cirri; 
larva large: 
No tentacular cirri; larva large: 
Larva with ventral mouth 
bordered by large lateral lps 
enclosing a “vestibule” and 
causing a ventral break in 
the continuity oof the 
prototroch; a pair of simple 
tentacles appear close behind 
the prototroch in the later 
stages; (the Trochophore of 
Nerine cirratulus is enclosed 
in a vitelline membrane 
characteristic of the species): 
643 
(Phyllodocidae.) (5) 
Syllidae. 
Nephthydidae. 
Phyllodocid A. 
Phyllodocid B. 
Phyllodocid GC. 
(7) 
