124 LIFE BY THE SEASHORE. 



Fam. Glyceridse. 



Glycera. Prostomium in G. capitata is very long, and bears four 

 minute tentacles at its tip, and a pair of minute palps at its 

 base. There are no gills. The dorsal cirrus is reduced to a 

 mere knob, and the. ventral is small. 



Fam. Arenicolidse. 



Arenicola. In A. piscatorum there are thirteen pairs of gills, and 

 a gill-less tail region behind these. 



Fam. Spionidse. 



Nerine. In N. coniocephala the prostomium is conical, in N. 

 vulgaris it is T-shaped. 



Fam. Cirratulidae. 



Cirratulus. In 0. cirratus a transverse row of tentacular filaments 

 occurs immediately behind the head. The gills are present 

 chiefly in the anterior region. 



Fam. Terebellidse. 



Terebella. In T. conchilega there are three pairs of gills placed on 

 segments two to four, and fourteen to seventeen pairs of red 

 gland-shields on the under surface. 



Fam. Amphictenidse. 



Pectinaria. In P. belgica the tube is straight. There are two 

 pairs of gills. 



Fam. Chlorhsemidse. 



Trophonia. In T. plumosa, there are two long tentacles and eight 

 short gills on the head, which is inclosed in a "cage" 

 of bristles. 



Fam. Sabellidse. 



Dasychone. In D. bombyx the back of the gill -filaments bears 

 distinct dark-coloured eyes. 



Fam. Serpulidoe. 



Pomatoceros. In P. triqueter the operculum is limy, and bears at 

 the sides two horny processes. 



NOTE ON DISTRIBUTION. 



Perhaps one of the most striking points in regard to the distribution 

 of the worms mentioned is the great size and abundance of Nereis 

 pelagica on the North-east, and its comparative rarity and small size 

 on the South and West. On the other hand, Nereis dumerilii is much 

 larger on the West Coast than on the East, and is apparently more 

 abundant on the former coast. The Sabellids are perhaps commoner 

 between tide-marks on the South and West. Generally, however, 

 the worms mentioned are widely distributed round our coasts, subject 

 to local variation dependent on food-supply, suitable localities, and 

 so on. 



