The following observations were made from a series of embryos and young larvae of Acipenser rubicundus, which were kindly sent by Mr. W. J. K. Harkness of the Canadian Fisheries to Professor D. M. 8. Watson at this college. I am much indebted to Professor Watson for the loan of this valuable material.

With Plates 10 and 11 and 4 Text-figures.

1

A similar method of closure to that in Polypterus occurs in Ceratodus.

1

Further complications have been introduced by those authors who contend that pro- and mesonephric canals may develop in the same segments, the pronephros being derived from a more ventral part of the mesoderm than the mesonephros, but this assumption is based on theoretical considerations, and has no real foundation.

Copyright © 1927 by the Company of Biologists Ltd.
1927
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