IV. 



V. 



III. 



VII. 



Pinnae of fronds of Ferns with sori ; I. Folysiichuni, the sporangia visible at the margin of 

 the peltate indusiuni ; II. Asplenuim; III. Picris aquilina; IV. the same with the 

 indusium thrown back to show the mode of attachment of the sporangia ; V, Poly- 

 fiodium, indusium wanting; VI. Hyiuefio/^hyUuvi or filmj' fern ; VII. the same ; the 

 indusium partly removed to show the sporangia (all magnified), p. 173. 



Elm : section through 

 the sepaloid peri- 

 anth, p. 131. 



Urtica dioica: I. staminate flower ; II. pistillate flower ; 

 III. fruit section (magnified), p. 130. 



{Opposite p. 17 = 



