BRITISH NAKED-EYED MEDUSA. 
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 Meduse, 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 flash 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 Medusz that they chiefly owe their phosphorescence. 
They belong to that section of Acalephze termed by Eschscholtz Discophore : the upper 
portion of the body being formed in the shape of a hemispheric disk. All the Discophorze 
may be conveniently arranged in two great groups: the first consists of those which have the 
eye-like bodies or oce/li 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 (sreyavoc, 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 Medusz, or Gymnopthalmata (yupvoc, 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 
