635 EXPLANATION OF THB PLATES. 



ISOBTES.— Plant of I. lacnBtrls (1) ; eporocorp containing mlnnte spores, cut across (2), 

 enlai^ed; same divided lengthwise (5); sporocarp with coarse spores, divided 

 lengthwise (S) ; and (4) three coarse spores uiore magnified. 



AZOLLA.^— Plant (1); aportionmagnified(2), with two kinds of organs; sterile sporocarp, 

 or antheridimn, more magnified (S) ; fertile sporocarp more magnified (4) ; the same 

 burst open, showing the stalked sporangia (5); one of the latter more magnified 

 (6) ; another bniBting (7) ; and three spores (8), beset with bristles. 



THE END. 



