ACALEPH^. 247 



cesses like hairs projecting from them. In no part of this horny tissue 

 is there a trace of a cellular or a reticular structure. 



The most singular incidents in the history of the Medusae are the 

 circumstances connected with their reproduction. They are all propa- 

 gated by eggs, which the females produce in glandular organs, some- 

 times arranged in bands or patches on the surface of the sub-umbrella, 

 and sometimes in cavities at the base of the peduncle. But these ova, 

 when excluded from the body of the parent, develop an animal quite 

 different in form from that from which they sprang ; and it is only in 

 the second generation that the original Medusa is reproduced. The 

 eggs are developed, to a certain extent, in small pouches, placed beneath 

 the body, and in the arms of the mother, whence they are not excluded 

 until they have acquired the form of an active infusorial animalcule, fur- 

 nished with cilia, enabling them to swim freely in the water. After a 

 time, the little animal attaches itself by one extremity in some suitable 

 position, and awaits its further development. Arms are soon formed 

 at its upper extremity, and it now presents the appearance and takes 

 its food in the manner of a hydraform polyp. At this stage of its 

 growth buds are often produced, just as in a true hydra. The body now 

 increases considerably in length, and becomes constricted, or divided 

 by wrinkles of the surface into numerous segments ; these become 

 more and more distinct, their edges become notched, and at length the 

 animal resembles a pile of jagged saucers placed one upon another, 

 and surmounted by a crown of tentacles. At length these separate, 

 and swim about like little Medusas; and, after undergoing some 

 changes, they acquire the form and colouring of the common Medusa 

 aurita of our coasts. So completely do what, for want of a better term, 

 we must call the preparatory state of these animals, resemble hydroid 

 polyps, that their connection with the Medusa has only been quite 

 recently discovered ; and the species just referred to has been described 

 under the name oiHydratvba; and from their great resemblance to 

 the Tubularian and Sertularian polyps, some zoologists have proposed 

 the removal of the whole of the hydroid polyps into the present 

 class, of which many of them are certainly only stages of development. 

 Opinions are stiU. so much divided, however, as to the true affinities of 

 these animals, that- we have preferred leaving the hydroid polyps in 

 their old position to placing them where few of our readers would think 

 of looking for them. 



Wonderfully beautiful as are these creatures in form and colour, the 

 amount of solid matter contained in their tissues is incredibly small. 

 The greater part of their substance appears to consist of a fluid, dif- 



