SOCIAL "CROWNED HEADS." 135 



Iii this group Megalotrocha albo-favicans 

 we seem to have reached the crown of social 

 rotatorial organisms. Individually, the size of 

 a Megalotrocha is about 1-3 6th of an inch in 

 length, a slender body, tapering off into a foot- 

 like tail, from which a sticky, gummy substance 

 unites it to its nearest neighbour and to the plant 

 or other object on which the whole colony rests. 

 It has eleven pairs of muscles, two jaws (with 

 teeth), water vascular canals, two eyes, cerebral 

 ganglia, stomach appurtenances, and reproductive 

 organs, all perfect, and in so small a compass ! 

 Yet are they the largest of all the associated 

 Rotifer a ; and, as a full-grown group expands 

 itself, one looks across their long and finely- 

 transparent bodies as through a forest of ani- 

 mated trees, the upper parts of which are dense 

 with the foliage of complex organs, while the 

 trunks are bare and transparent, standing out in 

 radiating, yet closely-compact, lines, through which 

 objects beyond are clearly visible. Of a sudden, 

 the whole forest-like colony contracts with a rush, 

 to which in imagination one may listen for the 

 sound. It is only for a moment, and again they 



