PLATE XXIV. 



[Proc. Wiish. Acad. Sci., Vol. Ill, PI. LVII.] 



Fig. I. Alaria fistulosa Post & Rupr. ; % natural size. 



2. " " " *' section of midrib ; natural size. 



3,4. " " " " portions of the midrib (X 80). 



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