INTRODUCTION TO CEYPTOGAMIC BOTANY. 439 



Hepaticce. Targionia has a Lichenoid frond slightly forked, 

 with a central midrib, porous above, and clothed below with 

 scales and rootlets, and often exhibiting a dark purple tint. 

 The sporangium is clothed by the remains of the archegonium, 

 without any proper involucre. The general involucre is 

 bivalvate. More than one archegonium is contained within 

 the sac at first, but of these one only is impregnated, or at 

 least one only comes to perfection ; the male fruit is in scaly 

 buds, which proceed from the lower side of the midrib, with an 

 exposed disc, in which the antheridia are deeply immersed.* 

 Sometimes the plant is dioecious, sometimes monoecious. The 

 spermatozoids are at first spiral, and then expanded with two 

 flagelliform delicate appendages (Fig. 91,/). The other genus, 

 Cyathodium, has also a bilabiate involucre, containing a single 

 sporangium, which splits above into, generally, six teeth, 

 coloured above. The upper portion of these teeth is formed 

 by the junction of many tubes of unequal length, transversely 

 striated ynth. semicircular fibres. It has, in fact, a sort of 

 peristome, but one, perhaps, only analogous with that of 

 mosses. It does not appear, at least from the description, 

 what precise relation it bears to the archegonium. The only 

 species occurs in subterraneous caverns, and in fissures of rocks, 

 which are never penetrated by the light. -f* Targionia varies 

 in the width and thickness of the frond, its form, and in the 

 comparative number of the pores. 



2. Jecoeaei^, Fees. 



Fruit produced on the under side of a pedunculate recepta- 

 cle, arising mostly from a transformation ot the margin of the 

 leaf Peduncle often sheathed or involucrate. Archegonia 

 always dependent. 



483. This tribe is placed here partly on account of its im- 

 mediate connection with Targionia, and partly because of the 

 intimate relation of Lunularia (Fig. 93, d) to Jungermanniw. 

 Jecorarice are especially remarkable for the peltate peduncu- 



* Mont., Ann. d. Sc Nat., a6r. 2, vol ix., tab. 3. 

 t Mont., Cuba, p. 191. 



