40 ACALEPHA. 



Localities. All the forms, at least in their adult 

 condition, are free swimmers in the sea. They 

 come to the surface in the finest, calmest weather, 

 and most abundantly in the latter half of the day, 

 and during the night, especially in summer and 

 autumn. They must be caught by means of a 

 muslin net drawn through the water, the bag of 

 the net being at intervals turned inside out into a 

 glass vessel of water, when the smaller specimens 

 captured will float off uninjured. Many, however, 

 are so transparent and so delicate, that they can 

 with difficulty be detected. 



Identification. Attention must first be paid to 

 the general form, whether umbrella-like, berry-like, 

 or irregular. If the first, which will generally be 

 the case, notice the eye-specks, whether exposed or 

 covered by flaps ; the number and condition of the 

 radiating vessels, and the position and form of the 

 ovaries. Finally, the shape of the umbrella, the 

 form of the peduncle, the number and arrangement 

 of the tentacles, the presence or absence of furbe- 

 lows, and the number and position of the eyes, 

 afford the distinctive marks of the genera. 



Authorities. For the general arrangement of 

 the Class, I have followed the " System der Aca- 

 lephen " of Eschscholtz, modified by Professor E. 

 Forbes. For the enumeration of native species, I 

 am indebted to the " Monograph of the Naked-eyed 

 Medusae" of the latter author, Dr. Gray's "Cata- 

 logue of British Radiata in the British Museum," 

 and my own personal observations. 



the reader is referred to Steenstrup's " Essay" (Ray Society), to 

 Professor Forbes's "Monograph of the Naked-eyed Medusae," 

 and to my own "Devonshire Coast." 



