INTRODUCTION TO CKYPTOGAMIC BOTANY. 455 



split almost to the l^ase ; elaters bispiral ; leaves w ith a folded 

 lobe at the base. 



499. This tribe is known by the lo])e at the base of the 

 leaves being simpl}^ folded njjon the larger lobe. In Radula it 

 sends out fine roots into the soil ; in Madotheca it is smooth. We 

 have lost .here the winged and angular perianths of Juhulece. 

 Madotheca platyphylla is one of our commonest species, form- 

 ing elegant tufts on walls. It assumes a great variety of forms, 

 and is common in the United States. Radula complanata 

 is scarcely less common on trunks of trees ; neither, however, 

 is confined to one habitat. There are a few other representa- 

 tives, but the greater part of the species belong to the tropics, 

 or warmer temperate regions. Gems are formed on the margin 

 of the perichffitial leaves in R. complanata. The leaves are 

 generally entire, but they are sometimes fringed or toothed. 



10. Ptilldie^, Nees. 

 Mastigophore^, Nees, Endl. Ptilidia, Nees. 

 Perianth often confluent with the involucre ; involucre poly- 

 phyllous, imbricated ; stem mostly pinnate ; leaves divided. 



500. This tribe contains many beautiful species, the greater 

 part of which beloug to the tropics. Ptilidiwm ciliare is a 

 common subalpine species, remarkable for the long setaceous 

 cilia of the leaves ; the perianth is still free. Polyotus is 

 an antarctic genus in which the perianth is wanting, the 

 leaves are lobed somewhat after the fashion of Frullania, 

 and some of the stipules have saccate lobes. Sendt- 

 nera has a few European species ; the branches are often 

 much attenuated at the tips and recurved, which gives them 

 a peculiar appearance. There is a perianth as well as an 

 involucre. Sendtnera diclados (Fig. 96, d) affords a good 

 example of the thick walled tissue with connecting ducts, which 

 occurs in many Jungermannice, as Jungermannia Tiirnetd 

 and Sendtnera Woodsii, to which attention was first called, I 

 believe, by Sir W. J. Hooker, as different from the ordinary 

 cellular tissue of the leaves of Jungermannice. Trichocolea 

 has a bristly involucre, and palmatifid leaves, which are, 

 moreover, so finely divided that they appear woolly. T. tomen- 



