170 BRITISH ANNELIDS. 



In some cases it is slimy, but clear ; sometimes it has a peculiar 

 smell, and frequently it is turbid. In one instance the mucus is so 

 thick and yellow that the medium has to be frequently changed if the 

 worms are to be well preserved. They are tolerably uniform in size, 

 the average length being about three inches. The setai are in four 

 couples, and the members of each couple are nearly close together. 

 The internal structure is interesting, and in the case of one new 

 species (A. mmdn'ca, Friend, not, however, found in Essex as yet), 

 it is only by the study of the internal anatomy that we can be abso- 

 lutely certain which species is under examination. I shall, however, 

 adhere as much as possible to my rule to make the identification of 

 species possible by the enumeration of external characters alone. 

 The foregoing account may be compared with the brief diagnosis on 

 page 109. 



SPECIFIC CHARACTERS. 



I. Allolobophora chlorotica, Savigny. The best known 

 member of the whole group is the Green Worm. It is one of our 

 most ubiquitous species, and may be readily recognised by its unique 

 appearance and habit. It is found in gardens and fields, but most 

 frequently under stones in pastures, or by the side of watering places 

 frequented by cattle. Here, an inch or two under the soil, or 

 covered by the stones and other things, it will be found sluggishly 

 coiled up in a ring, and looking very like a dirty, repulsive caterpillar. 

 Unlike the bulk of his brethren, he ignores the truth that 



" He who fights and runs away 

 May live to fight another day." 



He neither fights nor runs. Perhaps he feels secure in his ugliness, 

 or knows that, like the cuttle-fish or skunk, he can play a dirty trick 

 if need be, and cover his foe with foetid mucus. 



The worm, when extended, is seldom more than three inches 

 long, and the girdle appears to be in the centre of the body. This 

 is owing to the greater diameter of the front segments, which, though 

 only thirty in number, extend over as great a space as sixty behind 

 the girdle. Such variety exists in the colour, shape, size, and habit 

 of the worm that it will be necessary, when the details have been 

 more fully worked out, to create some new forms and varieties ; but 

 for the present we will put the whole of the forms under the aggregate 

 title. The colour ranges from sea-green, through a dirty green, to a 

 dull yellow or clay colour. Sometimes it is almost flesh-coloured. 



