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MEDUS.E OF THE WORLD. 



The name "Margelis" was first proposed by Steenstrup, 1850, and applied to designate 

 Margrlis principis of the North Sea, and this name was adopted hy Agassiz and Haeckel. 

 They would designate "Margelis" as being similar to Bougainvillia, but with a manubrium 

 having a narrow base devoid of a peduncle and with the 4 radial-canals opening close together 

 into the 4 corners of the narrow stomach. Bougainvillia, on the other hand, they would 

 restrict to designate medusae with a wide quadratic stomach and often with a peduncle, the 

 4 radial-canals arising far apart from the 4 corners of the wide cruciform stomach. While 

 these distinctions serve admirably to distinguish "Margelis" principis or "M." carolinensis 

 from Bougainvillia superciliaris, they fail completely to classify medusae in which the manu- 

 brium is of moderate width, neither wide nor narrow. It is my object to retain only positive. 



Fir,. 85. Bougainvillia "/r//Yo'/j," after Allman, in Ray Society, 1871-72. 



not relative, characters as of generic value. It is futile and confusing to attempt to separate 

 genera upon such intergrading differences as "wide or narrow stomach," "long or short manu- 

 brium," etc., for we generally find that species will be discovered allied evidently to both these 

 so-called "genera," but strictly intermediate in essential characters, Bong/iinvillia takes 

 precedence over Mar gel is and should therefore supplant it. 



Forbes, 1848, introduced the spelling Bougainvillea, but Lesson's original proposition is 

 Bougainvillia. 



Haeckel, 1879, p. 90, confuses the hydroid of Bougainvillia with EuJenJrium, but in 

 Eudendnum no free medusx are produced and there are other distinctions separating it from 

 Bougainvillia. 



