PLATE I. 



FIG. 



1. Clava multicornis, p. SO, of the natural size. 



2. Clava multicornis, magnified. 



3. An outline of the upper part or head of the Clava mul- 



ticornis, to show the oral aperture. From a drawing 

 by Professor Edward Forbes. 



4. Hydractinia echinata, p. 34, of the natural size. 



5. Hydractinia echinata, magnified. — This, and the pre- 



ceding figure, are from Professor Forbes 1 drawings. 



6. Synhydra parasites, Quatrefages, p. 33. — Copied from 



Quatrefages 1 figure in the Ann. des Sciences Nat. 

 n. s. xx, pi. viii, fig. 1. 



