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' drawings. 



6. SY.VHYDRA PARASITES, Quatrefages, p. 33. Copied from 



Quatrefages 1 figure in the Ann. des Sciences Nat. 

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



