AQUATIC WORMS 83 



remarkable that this family is more in evidence than any other, 

 for we can only presume that the more the arms the more the 

 food. Plumatella repens, the most common variety of this 

 family, has egg-shaped stato blasts. Lophophore, although not 

 so common, rejoices in the fact that it is the only species of 

 its kind. The Polypides are enclosed in a jelly-like glassy 

 case. 



As the colony increases in age it alters, becomes segmented, 

 the holes more deeply cleft, until, as one would expect, separa- 

 tion takes place. The divided part floats away to lay the 

 foundations of a subsequent colony. 



Lophophore has the power of movement, and is able to 

 wander to its " heart's " desire. Compared with the immobile 

 condition of Plumatella and many others, such freedom seems 

 " too good to be true/' Lophophore is no lover of excessive 

 exercise, and its travels, although of long duration, are not of 

 great distance half an inch is usually the maximum. The 

 undertaking of so great an enterprise takes twenty-four or more 

 hours to accomplish. 



Cristatella Mucedo is the great traveller amongst the 

 Polyzoa ; in fact it is especially equipped for a wandering life. 

 The outer' case has a flattened sole, on which the creature 

 moves. On the upper surface the colonists protrude their 

 plumes, seemingly perfectly contented in whatsoever direction 

 the foot is taking them. 



It is interesting to know that the base of the colony pro- 

 duces a thin film that oils the surface on which the creatures 

 are moving. Thus friction is minimised, and should the 

 direction lead downhill, and the colonists at the same time be 

 energetically waving, it is quite easy to follow what must 

 necessarily occur. On levels and uphill, if Cristatella does 

 walk uphill, matters are different. If the foot oils the surface, 

 it is doubtful whether the creature would be able to advance 

 in the latter case, but on the level, by reason of certain altera- 

 tions of the under surface of the sole, a slow movement would 

 easily result. It is peculiar that the movement is always in 

 the direction of the longer axis, and never sideways. This 

 fact would seem to denote that some of the creatures are 

 responsible for the steering, so that the direction is not a 

 matter of mere chance, as one is given to suppose. Colonies 

 of Cristatella mucedo are often as much as 4 to 5 inches long, 

 but very narrow, as although the colony is continually increas- 

 ing in length, yet the breadth does not. As time goes on 

 some of the community die, but no alterations are made, so 

 that the living and the dead remain together. In fact it 



