WORMS 



357 



other description of vegetable debris. They also swallow and pass through their systems large 

 quantities of earth, absorbing from it its organic constituents, and depositing the indigestible 

 residuum therefrom in the form of " earth-casts." The useful function thus performed by 

 worms in bringing up earth from considerable depths and redepositing it upon the surface of 

 the ground has been fully demonstrated in one of Mr. Darwin's works. There are some twenty 

 species of British earth-worms, none of which, however, attain to the proportions of certain 

 kinds indigenous to Australia and South Africa. Some of these giant species are as much as 

 3 or 4 feet long when unexterided, and will on the stretch measure twice such lengths. Their 

 thickness, which is proportionate, may vary from that of a man's finger to that of an ordinary 

 sausage. 



The most numerically abundant and structurally varied representatives of the bristle- 

 bearing worms are inhabitants of the sea, and are divisible into two easily recognised 

 natural groups. In one of 

 these the animals resemble 



earth-worms in their ability >^H ^^. 



to move about freely from 

 place to place. In the other 

 group they secrete and per- 

 manently reside within a tu- 

 bular edifice, which may be 

 calcareous and of shell-like 

 hardness, or composed of par- 

 ticles of sand, mud, or other 

 substances. The free-roving 

 group, which embraces by far 

 the larger number, includes 

 such forms as the LUG-WORM, 

 or LOB-WORM (held in high 

 repute for fishing-baits), and 

 a host of other allied species. 

 In all of these the develop- 

 ment of bristles and other 

 appendages is more pro- 

 i-xinccd than in the Earth- 

 worms. In another group, 

 known as the NEREIDS, the 

 elongate worm-like body is 

 more or less flattened in shape ; 

 unjointed leg-like appendages, 

 supplemented by bristles, are 

 developed from the majority of the segments, and the animal presents a somewhat centipede- 

 like aspect. This likeness is further enhanced by the presence of antennae-like organs at the 

 anterior extremity, while the mouth is armed internally with a pair of sharp-pointed, horny 

 jaws. In many of the nereids the lateral organs are flattened out and paddle-like, constituting 

 effective swimming-structures. Some of the larger species attain a length of several feet, and 

 are especially noteworthy for the brilliantly iridescent tinting of their skins. The palm of beauty 

 with respect to its brilliant colouring must undoubtedly, however, be awarded to the so-called 

 SEA-MOUSE, frequently cast up by storms on the British coast. In this creature the body is 

 comparatively short and thick, 3 or 4 inches long by i.V to 2 inches wide. The centre 

 of the back is covered in by a felt-like mass of fine interlacing hairs of a brownish hue. 

 underneath which are broad, flat scales which protect the breathing-apparatus. The sides arc, 

 however, thickly clothed with long, slender hairs and bristles, each of which reflects the 



Phte ly If. Savlllt-Knu, F.Z.S.] 



TUBE-WORMS 



Somt with their Jioivcr-like gill-tufts expanded 



[Milftrd-an-Sta 



