Physalia Pelagica. 235 



sea anemones. Pliny, who had probably more abundant 

 opportunities of observing the nature of this singular form 

 of zoophytic life, adopts the name of Aristotle, translating 

 it into Latin, as Urtica marina. Linnaeus, in modern times, 

 only knew this zoophyte from the account of it by Sir Hans 

 Sloane, in his description of a voyage to the West Indian 

 Islands, a curious and interesting work, the title page of which 

 announces that it is " illustrated with the things described, in 

 large copper-plates as big as the life." The description in this 

 work is, of course, very imperfect ; but the Piinian name, 

 Urtica marina is adopted, which Linnseus changed to Holo- 

 thuria physalis. The generic term Holothuria was, however, 

 erroneously adopted, under the impression that this zoophyte 

 was more nearly allied than it is to the Holithuridas, some of 

 which are, like the creature under description, very beautifully 

 tinted with h-idescent hues. The specific term physalis, from 

 the Greek, physe (cf>vcrr]) a bladder, was adopted by Linnasus 

 in consequence of the bladder-like form of the body, by means 

 of which this creature floats upon the surface of the ocean, 

 and this last name, so appropriately invented, is the one by 

 which the genus itself is now distinguished. Cuvier, one of 

 the first great general naturalists who succeeded Linnasus, 

 separated the Actinias from the Acalephge, placing the latter in 

 a separate group, as Acalephes fixes, their habit being to adhere 

 to rocks, in a somewhat plant-like manner. But afterwards, 

 following Eisenhardt, he placed the Actiniae with the Polyps, 

 and then separated the Acalephs into two divisions — Acalephes 

 simples, a division including the Medusas, or jelly-fish, and 

 Acalephes hydrostatiques, being those furnished with an appa- 

 ratus for floating on the surface of the water, in the form 

 of a bladder. The species under description formed the type 

 of the last named group, as Acalepha hydrostatica. The 

 term hydrostatica was not, however, so correct as the simpler 

 pelagica, from the Greek word IleXayo?, the ocean, because it 

 does not float at ivill, by the means of an apparatus under its 

 command, but simply from the reason that its structure causes 

 it to float on the surface of the ocean quite independently of its 

 own volition. Lamarck was the first to determine that the 

 conspicuous bladder-like body was in fact the chief generic 

 character of this singular creature, and he therefore transferred 

 the ingenious and characteristic name which Linngeus had only 

 made a specific one, into the more honourable position of the 

 generic appellation, making our Portuguese man-of-war assume, 

 in scientific classification, the distinctive title of Physalia 

 pelagica, or sea-bladder, which it still bears. 



In 1829, M. Eschscholtz, the Prussian naturalist (with whose 

 name every lover of flowers is so well acquainted, through the 



