NOTES ON A NEW ROTIFER. MELICERTA 

 COLONIENSIS. 



By W. R. Colledge. 



(With plate XI). 



( Read before the Royal Society of Queensland, 30th September, 



1918). 



The present note is a description of what seems to be 

 an entirely new species of colonial rotifer of the family 

 Melicertadae, order Rhizota. The}' occur as circular 

 masses of tongh yelloAv gelatinous matter, a quarter of an 

 inch or more in diameter. Occasionally they encrust the 

 stems of water plants but oftener are found on submerged 

 pieces of loose bark. In the latter case the form is hemi- 

 spherical. Two hundred individuals Avere counted in one 

 colony, not quite a quarter of an inch in diameter. Like 

 most colonial rotifers, the feet of each individual are placed 

 at the centre, and the bodies radiate on all sides. The head, 

 or trochal disc, is ver}^ large and shaped like a four-leaved 

 shamrock. Duiing narcotization, at first, musc^ilar control 

 relaxes, and the organ becomes circular like the flower of 

 the pansy. This phase parses, and the ordinary melicertan 

 outline appears. 



Occasionally, an additional contraction is seen, and a 

 fifth smallei petal forms, frequentlj' at the top, bxit occasion- 

 ally on the loMcr edge of the disc. In fixing the animal for 

 preservation, the outline becomes much squarer than it 

 is in a natural state. A line of strong cilia borders the 

 disc forming the principal wreath. Lying within this is 

 the secondar}^ wreath, formed of much shorter and finer 



