﻿OF THE ACALEPHS OF NORTH AMERICA. 253 



The question about the value of the position of the ovaries is one of great impor- 

 tance. In Sarsia and Hippocrene, we have the eggs developing upon the external walls 

 of the proboscis or central digestive cavity. In Tiaropsis, Thaumantias, and others, we 

 have the ovaries on the outer surface of the radiating tubes, while in Staurophora we 

 have them in an intermediate position. This last fact shows the little importance there 

 is in the position which the sexual organs assume in these animals ; for, even if we had 

 not this intermediate disposition in Staurophora, I would not hesitate to bring together 

 genera like Slabberia and Sarsia, which can hardly be distinguished as genera otherwise 

 than by the disposition of the ovaries ; and though Circe has eight radiating tubes, and 

 eight ovaries, this difference does not remove it in the slightest degree from Thaumantias. 

 Circe and Thaumantias are as nearly allied as genera of the same family can be, and, 

 indeed, between them there is no other difference than in the number of radiating tubes ; 

 and we know already, from Sarsia, that this is of little value. Saphenia, also, when 

 compared with Oceania, may show the slight importance these numbers have ; for the 

 value of the genus Saphenia as a generic section may fairly be questioned, when we 

 see Oceania with four, with eight, and with more tentacles, the chief generic character 

 of Saphenia being to have only two such appendages. 



Now if the position of the ovaries around the central part of the digestive cavity, or 

 upon its radiating tubes, is not a character of sufficient importance to warrant a distinc- 

 tion of higher order than a generic distinction, we can be led to a more natural arrange- 

 ment of the genera of this family than that proposed by my friend, Professor Forbes ; 

 but I do not wonder, that, with all his philosophical acumen, he has been led to exagger- 

 ate the value of these characters, for he first pointed them out, he first recognized these 

 fundamental differences, and we all know that the first step in the recognition of facts 

 is to exaggerate their value, and that we hardly come to a correct appreciation of their 

 real importance unless we have exaggerated them. This kind of natural exaggeration 

 is, after all, the only test of the value of facts ; and I have no doubt, that, in his own 

 mind, and probably by the progress he has made since he gave the scientific world the 

 admirable results of his investigations, Professor Forbes himself must have found 

 that the distinction of six families among naked-eyed Medusa? does not rest upon 

 the existence of six fundamental types of structure, but upon various combinations of 

 the fundamental elements of one very natural group, for the recognition of which we 

 are indebted to him. 



Though groups more or less similar to that of the naked-eyed Medusa;, as circum- 

 scribed by Professor Forbes, have been introduced in former works upon the natural 

 history of this class of animals, — though we have in Eschscholtz the families of 



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