DESCRIPTION or THE PLATES. 



PLATE I. 

 Cristatella mucedo. 



Fig. 



1. Cristatella mucedo ; an adult specimen, adhering to the submerged stem oi Ranunciilm 



aquatilis. Of the natural size. 



2. The same enlarged. 



3. Statoblast of Cristatella mucedo in an early stage; it is surrounded bv a ciliated mem- 



brane, and there is as yet no appearance of the marginal spines. 



4. Tlie same more advanced ; the enveloping membrane is destitute of ciUa, and the spines 



have begun to grow out from the maroin of the disc. 



.5. The same, still further advanced ; the spines have impinged on the enveloping mem- 

 brane. 



6- The mature statoblast; the enveloping membrane has been torn by the pressure of the 

 spines, and has disappeared, and the statoblast has become free. 



7. The same, viewed on the edge. Figs. .3 — 7 are magnified about 50 diameters. 



8. Natural size of mature statoblast. 



