PLATE 12 



EXPLANATION OF FIGURES 



Cross-sections of metamorphic stage I. X28 



29 Level corresponding to larva, figure 7, showing presence of M. genio- 

 hyoideus lateralis anteriorly. 



30 Level corresponding to larva, figure 9, showing the deepening of the 

 groove at which the branchial plate articulates with the basibranchial, and the 

 anterior growth of the abdominohyoideus muscle. 



31 Level corresponding to larva, figure 10, showing development of the 

 abdominohyoideus, and absence of change in other particulars. 



32 Level corresponding to larva, figure 14, showing the anlage of the adult 

 epibranchial and beginning of degeneration of the larval first epibranchial. 



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