THE PULMONIGRADE ORDER. 221 



centre of which on the concave side depends a cluster of 

 variously fringed and lobed vessels, which constitute the 

 digestive system of the animal, while numerous slender 

 fibres or teutacula hang from the border of the umbrella- 

 shaped disc. Such a creature resembles an animated 

 mushroom, with its gills and stalk. Sometimes the 

 stalk is reduced to a minute point, and there are very 

 many modifications. The motion in all Jelly-fishes of 

 this shape is accomplished by alternate contractions and 

 expansions of the umbrella, repeated at regular inter- 

 vals, something like the movement of the lungs in re- 

 spiration, in allusion to which resemblance this order of 

 Jelly-fishes has been called Pulmonigrade. The convex 

 end of the umbrella is directed forwards, the fimbriated 

 vessels and tentacula stream behind, and the creature is 

 propelled with a steady and graceful motion, very rapid 

 in some species. Unsightly and repulsive as the Jelly- 

 fish looks when stranded and lying exposed among sea- 

 wrack on shore, it is a most beautiful animal when 

 expanded in its native element and moving along in 

 freedom. Nor is it so defenceless as its low organization 

 and the softness of its parts may lead us to suppose. 

 Many of the species are capable of inflicting a sharp 

 and painful sting, sufficiently strong to paralyze the 

 animals on which they prey, or perhaps to ward off 

 danger when attacked by superior foes; while the long 

 tentacles with which most of them are furnished are 

 admirably adapted for seizing prey, as they adhere to 

 whatever comes within their reach. A complete work 

 on British Medusae is still a desideratum, but the task 

 has been commenced by Professor Edw. Forbes, whose 



