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polyps which grow in the neighborhood of Boston, a species 

 of the genus Syncoryne. The species comes nearest to 

 Syncoryne Listeri, Van Beneden, from which it differs 

 however, in being less branched. 



As this polyp was covered with buds, Mr. Desor was induced to 

 follow up its development, which led him to the result that these 

 buds give rise to those little jelly-fishes, which are found in so 

 great abundance about the wharves of Boston during the months 

 of April and May, and which have been described under the 

 name of Oceania tubulosn. 



The formation and growth of these buds or embryos is very 

 simple. A kind of hernia is formed in the outer membrane of 

 the polyp. Into this the alimentary (sap-like) liquid, which 

 circulates through the stem of the polyp, enters, eddies in it, as 

 in a reservoir, and flows out again. As the bud grows the liquid 

 is seen to penetrate into it in four other directions, and to form 

 thus the four accessary channels which surround the central res- 

 ervoir, and are easily recognizable by the same red color. At 

 the summit of these four accessary tubes are then seen four black 

 spots, which are the so-called eyes of the embryo Medusa. 

 When the bud has reached the size of a large pin's-head, it 

 extends from its interior four threads, being the prolongations of 

 the four accessary channels, which become the four tentacles 

 or nettling organs of the young Medusa. One day Mr. Desor and 

 Mr. Cabot saw a large number of buds or embryos in this state, con- 

 tracting violently, evidently in order to break the peduncle by 

 , which they were attached to the polyp stalk. This they succeeded 

 in doing, and moved freely about in the water, like Medusas. 

 The central reservoir was then closed up at the top, where a 

 navel was formed, and became the stomach of the Medusa ; 

 whilst a new opening appeared at its opposite extremity, which 

 was the mouth. 



Similar metatnorphoses were some years since traced in dif- 

 ferent polyps, and several authors have pointed out the resem- 

 blance between these buds and some small Medusae ; but they 

 have generally looked upon it as a mere analogy. Thus Loven 

 considers them as the female polyps. Steenstrupp regards them as 

 nurses ; and he suggests the idea that many small Medusae might 



