WORMS, ROTIFERS, LEECHES, POLYZOA 85 



worm, seizing its prey by means of a pair of sharp, hooked jaws. 

 The White Cat Worm (Nephthys margaretacea), which measures 

 from 6 to 10 inches in length, lives in rather firm sand between 

 half- and low-tide mark, and has a beautiful pearly lustre. Many 

 species of Nereis undergo considerable modification of form as 

 they become sexually mature, those segments containing the 

 generative products becoming greatly changed in appearance, 

 while the front part of the body remains comparatively unaltered. 

 So great is the change in appearance, that the mature worms were 

 for a long time supposed to belong to a different genus, and were 

 called Heteronercis, a term which is now retained to designate 

 this particular stage in the life of the worm. In this heteronereis 

 stage the males have fewer unaltered anterior segments than the 

 females. 



A species also known locally as the " Red Cat Worm " (Nereis 

 cultrifera) is fairly common on our southern coasts, where it 

 attains a length of 6 inches. The illustration facing page 76 shows 

 the formidable jaws of this worm, and in shape it very closely 

 resembles N. diversicolor. 



A most remarkable little Nereidiform Worm is the Tomopteris 

 scolopendra, with its hammer-shaped head and long antennae. At 

 certain seasons it is not at all uncommon off our shores, where it 

 is frequently taken in the naturalist's tow-net. 



The Phyllodocidae, or Leaf-bearing Worms, are easily distin- 

 guished from all the other Annelids by the double row of leaf-like 

 cirri on each side of the body, forming a border immediately above 

 the insertion of the feet (parapodia). The Leaf-bearing Worms 

 are swift in their movements and very graceful swimmers. The 

 Paddle Worm (Phyllodoce laminosa) is generally a bright bluish 

 or yellowish-green colour, and may grow to 24 inches in length. 

 During the daytime it lurks under stones and old shells, coming 

 forth at night to seek its prey. Many of the marine worms become 

 phosphorescent at night, glowing with a bright and steady light, 

 and one of the most interesting examples is the extraordinary 

 Vari-footed Worm (Chatopterus variopedatus), figured facing page 

 89, which shines with a strong greenish or azure-blue light, 

 and builds a long U-shaped tube in which to live, composed of a 

 parchment-like substance coated externally with sand and small 

 stones. 



