CLASSIFICATION. 27 
ScHIZ#ACE#.—Sporangia ovoid or pear- a. sessile 
or shortly stalked, having a complete, trans- : 
verse, articulated ring at the apex, which is 
cap-like and circular, and it therefore splits 
longitudinally. In our typical genus Lygo- 
dium the two pinnz at the base of each 4 
primary branch of the leaf have a flatly Uf 
expanded lamina definite in its growth. } 
The fertile segments are spicate, and each 
bears on its under side two rows of sporan- 
gia, each of which is placed in a pocket- 
shaped outgrowth of the tissue of the leaf 
(Sachs). (Fig. 3.) See also Plate XLIX. 
OsMUNDACE#&.—Sporangia globose, shortly stalked, 
opening into two valves by a longi- 
tudinal slit. They are unsymetric- 
{\\) ally rounded, and, instead of a ring, 
\\,) are furnished on one side with a pe- 
culiarly developed group of cells 
beneath the apex (Sachs). In our 
genus, Osmunda, from the distribu- 
tion of the sori upon the surface of 
the leaf, instead of upon the veins, 
the fertile leaves become contracted 
and no longer resemble the sterile 
fronds. (Fig. 4.) See also Plate LI. 
OPHIOGLOSSACE&.—Sporangia spiked, 
destitute of a ring, naked, coriaceous and 
Opaque, not reticulated, opening by a 
transverse slit into two valves, discharg- ‘ 
ing copious powdery spores. According >... 
to Sachs the sporangia of Ophioglossa- Fig. s. 
cez are so essentially different from those of other ferns 



