BRITISH HEPATIC^E. 51 



Badula, Dumort. Comm. Bot. p. 112, ex parte (1822). 



Eadula sect. Plagiochila, Dmrt. Syll. Jung. p. 42 (1831). 



Plagiochila, Dmrt. Rev. Jung. p. 14 (1835) ; Nees et Mont, in Ann. Sc. Nat. ii. 

 ser. V. p. 52 (1836) ; Lindenb. Sp. Hep. Fasc. i. (1839). 



Plagiochila, Sect. I. Asplenioidece, N. ab E. in Lindl. Intr. Nat. Syst. ii. ed. 

 pp. 414 et 452, n. 91 (1835), et Leberm. Eur. iii p. 518 (1838). 



_ Pructiflcation terminal, or from the growth, of innovations 

 axillary, autoicous or dioicous. Oolesule laterally compressed, 

 ancipital, erect or decurved at the apex ; mouth obliquely trun- 

 cate, bilabiate, entire or ciliate dentate. 



Involucral bracts two, larger than the cauline leaves, erect. 



Pistillidia numerous. Capsule of thick texture, quadrivalved. 



Elaters bi-spiral, attached to the centre of the valves. 



Androecium spicate, terminal or interrupted. 



Perigonial leaves smaller, ventricose, closely imbricated in two 

 rows, enclosing 2-3 oval antheridia. 



Plants conspicuous, growing on rocks or the trunks of trees. 



Primary shoots leafless, creeping, radiculose ; branches ascend- 

 ing or procumbent, simple, dichotomously branched, or dendroid. 

 Leaves succubous, distichous, or subsecund; dorsal margin de- 

 current, reflexed, entire, ventral arcuate, apex decurved, entire or 

 variously cut and fringed. 



Amphigastria inconspicuous. 



Derivation — irT^dyios, oblique, and p^srAoj, Up. 



Obs. — The present genus is one of the most natural among the modern groups of 

 Hepaticse. Indeed, there is a strong family likeness running through all the species, 

 so that the cultured eye can pick out a Plagiochila as readily as a Rose, or Willow. 

 But this very circumstance renders the separation of one species from another a matter 

 of no small difficulty, so that we find much difference of opinion as to which are to be 

 looked upon as permanent forms, and which varieties only. 



From allied genera Plagiochila may be distinguished by the laterally-compressed 

 oolesule, dimidiate leaves, which are neither auricula te (Porella), or lobed either on 

 the dorsal (Scapa/nia), or ventral aspect {Radula). 



The genus is represented in Europe by five species only, the whole of which are 

 inhabitants of the British Isles, and special to our western shores. 



But in tropical and sub-tropical regions the species are much more numerous, 

 and constitute an important part of the cryptogamic vegetation. In the Sjnop. 

 Hepat. p. 625, 32 species are described as Asiatic; 12 African; Northern and 

 tropic America, 89 ; Cape Horn, 9 ; and New Zealand, Australia, and the Antarctic 

 Isles, 30. 



But numerous additions have been made to this list since the publication of that 

 celebrated work. Thus Dr. Gottsche, in his Mexican Hepaticse (1863), describes as 

 natives of that country only 168 species; and probably Dr, Spruce, from hia rich 

 Amazonian gatherings, could add an equal number. 



Many of the Plagiochilse are noted for the elegance of their fronds, their fern-like 

 delicacy of form, and the variety and richness of their colouring. Such species as 

 P. a/rhuscula, P. Stephensonioma, P. gigantea, and P. svperbamnj well claim comparisou 



