BRITISH NAKED-EYED MEDUSiE. 



The creatures which I am about to describe and delineate in the following monograph 

 are animals of very simple organization and beautiful form. They are members of the lowest 

 section of the Animal Kingdom, and are intimately allied to the polypes, as we shall see when we 

 come to consider their classification, which will be best understood after we have examined their 

 structure. They are mostly minute, often microscopic, though many of their nearest relations, 

 such as the great stinging Medusae, grow to a considerable bulk. They are active in their 

 habits, graceful in their motions, gay in their colouring, delicate as the finest membrane, 

 transparent as the purest crystal. They abound in the sea, but are not equally plentiful at 

 all seasons. They have the power of emitting light, and when on a summer's evening the 

 waves fla|Ji fire as they break upon the shore, or glow with myriads of sparks as they curl 

 and froth around the prow of the moving ship or under the blade of the striking oar, it is to 

 delicate and almost invisible Medusae that they chiefly owe their phosphorescence. 



They belong to that section of Acalephse termed by Eschscholtz Biscophoree : the upper 

 portion of the body being formed in the shape of a hemispheric disk. All the Discophorse 

 may be conveniently arranged in two great groups : the first consists of those which have the 

 eye-like bodies or ocelli of their margin protected by more or less complicated membranous 

 hoods or lobed coverings, a character which accompanies one of great importance, viz. their 

 possession of a much ramified and anastomosing series of vessels. This section I propose to 

 name Steganopthalmata (anyavoQ, covered). 



The second division includes all those which have the ocelli naked, often aborted, and 

 which possess a very simple vascular system, the circulating canals proceeding to the margin 

 either altogether unbranched, or if divided, not anastomosing with each other. These I term 

 the naked-eyed Medusae, or Gymnopthalmata (yvfivog, naked). 



It is to the history of the British species of the second division that this monograph is 

 devoted. The observations embodied in it are the fruit of several years' research, having 

 been commenced in the year 1839, and continued every summer, either in the British seas or 

 abroad, until the autumn of 1846, when an account of them was read, for the first time, at the 

 Southampton Meeting of the British Association. That year and the previous summer were 



