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Prof. E. Warren. On the Development of the 



developed, and at every future moult the swimming ramus gradually 

 becomes shorter. Eelatively the mandibles travel somewhat forwards, 

 so as to be situated nearer to the mouth. The rudiment of the second 

 maxilla is just visible, that of the first maxilla is only seen in a 

 horizontal section of the embryo. 



Fig. 2. — Dorsal view of metanauphus. The embryonic carapace, formed bj the 

 fusion of the two dorso-lateral swellings, is gradually extending backwards 

 over the thorax, x 110 diameters. 



In these nauplii, I met with a remarkable instance of unequal 

 development in the different organs. Several nauplii which were 

 presumably older than those with a rounded posterior end (since they 

 were somewhat larger and possessed caudal forks) were, nevertheless, 



