ii § 70. . THE ACALEPHAE. 73 



of the hypotheses suggested in the above note, the embryos of Medusae and Polypi may be the 

 Hitherto there has been much confusion on this foundation of many other important changes. At 

 subject, from the want of complete series of obser- present, however, broad generalizations must be 

 vations ; even now the whole class can be regarded deferred until we have extensive and serial re- 

 only in a somewhat transitionary state, in a zoological searches in the embryology of these animals. For 

 point of view. Many genera which have hitherto separate details on the development of some forms, 

 been regarded good and permanent will no doubt, see Busch, loc. cit. (Sarsia, Lizzia, Cephea, Eu- 

 as Siebold has remarked, prove to be only unde- doxia, Diphyes) ; Huxley, loc. cit. (Diphyidae, 

 veloped forms of well-known species. As already Physophoridae) ; Agassiz and Desor, loc. cit. 

 stated, Jg-a«siz regards the Ilydroid Polypi as true (Medusidae). — JBd. 

 Acalephae, and the analogy which exists between 



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