PLATE XXIV. 



[Proc. W..sh. Acad. Sci., Vol. Ill, PI. LVIL] 



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



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



3,4. " " " " portions of the midrib (X 8) 



[476] (240) 



