HEPATICsE 



161 



forms have, except in Haplomitrium, a bilateral structure resembling that 

 of the Marchantiaceae ; rhizoids and rudimentary foliar structures are 

 formed on the under, the sexual organs on the upper side. In the 

 foliose forms the leaves, always very small, are frequently bisected or 

 bilobed, the lower lobe or auricle being the smaller one, and amplexicaul 

 or concave. Goebel states that in Java many of the Jungermanniaceae 

 are epiphytic, and that in these the auricle is frequently hollowed out 

 into the shape of a pouch or pitcher, serving as a receptacle for water 

 (fig. 140). In some species of Physiotium (N. ab E.) this receptacle is 

 prolonged into the so-called 'tubular organ.' The leaves of the foliose 



FIG. \^.Fossombroniaptisilla^. ab E., male 

 plant, a, natural size ; b, magnified. 



FIG. 134. Calypogeia. Trichomanis 

 Cord, (magnified). 



species consist of a single layer of cells without even the rudiments of 

 vascular bundles. There are species which form a connecting link 

 between the foliose and the thalloid Jungermanniaceae. The mode of 

 branching varies greatly, but growth always takes place by means of a 

 three-sided pyramidal apical cell. 



As respects the sexual organs, some species are monoecious, others 

 dioecious. In the foliose genera they are usually formed at the apex of 

 the primary shoots or of special small fertile branches, which have often 

 an endogenous origin on the ventral side. These constitute the acro- 

 gynous section of the order, which includes all the foliose genera except 

 Haplomitrium. In the thalloid genera, or anacrogynous section, they 



M 



