A Prominent objection to the association proposed by me of the Tunicata as a subdivision “Urochorda “with the “Cephalochorda” (Amphioxus) and the “Craniata “in one group, for which the name “Vertebrata” is retained, has been the fact especially put forward by Gegenbaur, that the Urochorda (Tunicata) do not exhibit any “vertebrate “structure, that is to say, a division of the body into myotomes. For a similar reason Balfour, whilst accepting the three-fold division of the Vertebrata, has proposed to denominate that group “Chordata,” and to restrict the term Vertebrata to the craniate division of the Chordata, thus excluding the Cephalochorda, as well as the Urochorda from the application of the term “vertebrate.”

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