8646 



Annelides. 



and thither so incessantly, that we are for a while confused, and can 

 make out nothing. We must fix our eye on some individual filament, 

 and watch that heedless of all the rest. Now we perceive that the tip 

 of this is bent over outwardly until the inner face is in contact with 

 the bottom, the pinnae expanding over the clay like the legs of the 

 letter A. In an instant these close together, seizing, as with many 

 opposed fingers, a little of the soft and impalpable clay, and at the 

 same instant the filament is straightened from its recurved condition, 

 and we perceive a minute pellet of clay lying between the pinnae. 

 The pellet takes a lengthened form, and presently glides quickly and 

 equally along the groove of the pinnated filament towards the mouth 

 carried along by means of the cilia with which every part is clothed. 

 Glancing at other filaments on each side we see a similar pellet in each, 

 at least of those which, as the disk lies, are in contact with the bottom. 

 As we follow the tiny mud pellets to their destination we trace them 

 to the mouth, where the two pointed tentacles stand guarding 

 the entrance. These appear to guide the united pellets to the poste- 

 rior orifice between the fans, through w r hich we see the lump making 

 its exit. 



We can learn nothing more of its progress from this point of view, 

 but let us now direct our lens to the side of the animal. Here we 

 again see the soft lump emerging -between the fans, and as it pro- 

 gresses the moveable fleshy flaps above described receive it and guide 

 it to the edge of the tube, plastering it as if with trowels on the edge, 

 regulating its thickness and smoothing it down. Meanwhile the animal 

 slowly revolves on its long axis, by which means all of the filaments 

 in turn are brought within reach of the ground, and thus the labour 

 of feeding the trowels is fairly distributed, and also the deposit is made 

 in succession upon every part of the edge of the tube. 



The tube increases in length by means of this process with con- 

 siderable rapidity, and it is not long before the animal is once more 

 completely protected. Probably as the desertion of the tube was in 

 this case voluntary, it is not unreasonable to infer that the formation 

 of a new habitation is normal, and takes place at certain though pro- 

 bably irregular intervals through life. There seems to be an inner 

 layer of gummy matter secreted from the collar on which the mud 

 pellets are moulded ; and often the lower portion of the tube — the first 

 formed — is found in this class of worms firmly adherent to a stone, 

 and consisting almost wholly of this gummy matter without any mud 

 coating. The substance, which hardens in water and is insoluble, is 

 of a horny texture and colour, a pellucid yellowish brown, and is pro- 



