328 



POLYCHAETA 



(Gills equal. 

 I Eye-spots. 



Nicolea. 



throughout the 

 body; commenc- 

 ing on the third 

 segment. 



P;11 



Jllls 



I Gills unequal and t 



I of peculiar shape. Pwto " 



/-arborescent ; 3 pairs. Leprea. 



I filiform ; in trans- 



j verse series in two 



[ segments. Thelepus. 



Amphitrite johnstoni Mgrn. (Fig. 175) is brown in colour, 

 about 4 to 6 inches in length, and nearly ^ inch in breadth 

 anteriorly. Each of the gills consists of a curved stem ; from the 

 convex side of which arise a number of branches, themselves 

 dichotomously divided, the final branches being long (Fig. 176, A). 

 There are twelve ventral " gland shields." The worm is fairly 

 common between tide-marks, below stones in muddy places : the 

 end of its tube of mud projects above the surface. Atlantic. 



Terebella (Polymnia} nebulosa Mont, is distinguished by its 

 bright red colour, spotted with white; it is 6 or 7 inches in 

 length, and ^ inch across. Large specimens of this beautiful 

 worm may be obtained at Weymouth and elsewhere on the south 

 coast, where it lives in about 14 fathoms. Each gill appears 

 much more arborescent than in the preceding (Fig. 176, B) ; it 

 consists of a main stem, from which comparatively few branches 

 arise ; these subdivide frequently, and the terminal branchlets 

 are quite short. The "gland shields" are fourteen to sixteen 

 in number. The tube is of mud. North Sea and Mediter- 

 ranean. T. (Leprea) lapidaria L. is 1 inch in length, orange-red 

 in colour ; and has 1 2 ventral shields. The tube, of fine mud, lies 

 horizontally on the under surface of stones. 



T. (Lanice) conchilega Pall, (the " sand mason ") forms a 

 very characteristic tube of sandy particles, small pebbles, and 

 pieces of shell. It is buried in the sand, but a short portion 

 protrudes, and bears, set round its edge, a fringe of branch- 

 ing sandy threads (Fig. 153) commonly seen on sandy shores 

 between tide-marks. The worm may be distinguished from the 

 preceding species by the fact that the series- of fourteen to seven- 



