EXPLANATION OF PLATES. 



The figures of the animals have been drawn upon the stone under my supervision by 

 Messrs. J. Reekie and A. Pollock, to whom I am indebted for the pains they have taken 

 to carry out my wishes. Most of the details of tentacles, suckers, &c., have been copied 

 from my own drawings, made with the assistance of the camera. For drawings of some 

 species I am indebted to Professor Steenstrup, as is indicated on the plates where they 

 are figured. 



