108 LIFE BY THE SEASHORE. 



supply of mucus which is here used to line the burrow. 

 The worm occurs between tide-marks, and is sometimes to 

 be found by digging near the rocks, while at other times it 

 may be found swimming freely. It is a somewhat local 

 form, but Granton and St. Andrews may be mentioned as 

 places where it is to be found. 



It is hardly necessary to enter in detail into the characters 

 of the worm ; the size, the colour, and the structure of the 

 parapodia render it easily recognised. 



The species of Nereis are very abundant on the shore 

 rocks, and are certain to be encountered in shore hunting. 

 With the Polynoids and the Phyllodocids they constitute 

 the commonest and most highly developed of the large free- 

 living worms of the shore. In all three sets the body is 

 very uniform in structure throughout its length, the head 

 is well furnished with various tactile processes, and the 

 parapodia are large and well developed. In studying the 

 bristle-worms, therefore, it is well to become familiar with 

 the common members of these three families before pro- 

 ceeding to the more difficult sedentary forms. Related 

 to these three families are two small families of sand- 

 inhabiting worms, which have much less conspicuous tactile 

 processes on the head, and considerably less brightness of 

 tint. These are the Nephthydidse, including Nephthys 

 hombergii, the " white cat," and the Glyceridoe, including 

 Glycera capitata, both interesting and curious worms. 

 Both are genuine burrowers, to be found along with many 

 other worms by digging in sand marked by worm -tracks 

 and burrows. When turned up by the spade both (Us- 

 play active movements, during the course of which the 

 enormous introvert is constantly protruded and retracted, 

 with a rapidity which is astonishing, and even alarming 

 to timid people. The performance suggests a juggler's 

 trick, in that the ejected proboscis seems bigger than the 

 worm. In both cases the introvert is an important instru- 

 ment in burrowing. 



The " white cat " (Nephthys hombergii) is common in the 

 sand in most places, and is valued by fishermen as bait. 

 The colour is greyish and sandy, but the body displays fine 

 opalescent tints. Usually the worm does not reach a length 

 of more than three to four inches, and it is remarkable in 



