74 BRITISH HEPATIC^. 



Mitten, in his numerous contributions to Hepaticology, follows Dumortier in 

 associating Sca/parda with Radula, in the division with incubcms leaves. 



The leaves of Scapania are peculiar, inasmuch as both the larger and smaller 

 lobes are attached to the stem by distinct decurrent roots, which are nearly opposite 

 to each other, so that it is difficult to say which is inserted lowest. But by careful 

 dissection and comparison with other species, I think little doubt can remain that the 

 leaves are truly sucouhous. On the other hand, the spiral is reversed in Radula, 

 which has undoubtedly incubous leaves. Upon this question, I may quote a passage 

 from a letter of Dr. Spruce (July 1874), whose critical remarks are always worthy of 

 attention. Afber stating that he is inclined to place Scapania in an intermediate 

 section with transverse leaves, he continues, — " the folia transversalia often (not always) 

 correspond to the ' foHa verticaUa ' of Martins and "Nees. But the actual insertion is 

 (as you know) rarely in a straight line, whether transverse, longitudinal, or diagonal, 

 and cannot be correctly described by a single word. It has seemed to me that 

 £lephwrostoma~wiis well distinguished from Lepidozia by its transversal leaves — neither 

 succubous nor incubous. Scapania has its leaves succubous as to the larger, incubous 

 as to the smaller lobe ; so that how you call them depends on ' which side you look 

 at the shield.' I consider them succubous.'' 



A few words as to the limits of the genus. Mr. Mitten, in his later works, has 

 reunited the Scapanoid Jungermannife {Diplophyllimi, Dumort.) with Scapania, because 

 the colesule, in some species of the latter, is imperfectly compressed. But in none of 

 the species is it contracted at the mouth, or (with the exception of *S'. curta) plioate- 

 angulate, as in D. albicans, <fec. Moreover, the naked, persistent, rhizomatous shoots of 

 Scapania are never met with in Diplopliylhnn. The same remark applies to Junger- • 

 mannia proper, in which growth is strictly acrogynous, the lower part of the stem 

 decaying, as new shoots are formed at the apex. 



The Sca2xmi(B constitute a small group, confined, for the most part, to the northern 

 temperate zone, the genus being replaced in the southern hemisphere by Schistochila, 

 Dumort. (Gottschia). Such forms as J. densi/olia. Hook., J. chloi-oleuca, Tayl., &c., in 

 habit approach Diplophyllum, but when the fructification is known, will probably be 

 found to constitute a distinct genus. In the Synopsis Uepat., N. L. G., fourteen species 

 are described as European (or if Dr. Lindberg's statement is correct that *S^. Tyrolemis 

 N. ab E. is only a yariety of S. cequiloba, thirteen) of which twelve are natives of 

 Britain. The estimation in Dumortier's Hep. Eur. (1874) is larger, twenty-two species 

 being enumerated. But several of these have hitherto been accounted varieties, and 

 of others, recently described by De Notaris, our knowledge is yet imperfect. 



a. Leaves longer than broad, lobes more or less acute. 

 1. Scapania nemorosa, Dumort. 



Pl. v. Fig. 15. 



Laxly csespitose ; shoots erect, decurved ; leaves pale-green, 

 smooth, accrescent, reraote, unequally bilobed ; inferior lobe obo- 

 Aate, convexo-recurved ; lobule scarcely half as large, cordate, 

 ficufe, incumbent; margins densely ciliate-dentate ; colesule half 

 immersed, obovate ; mouth truncate, ciliate ; capsule ovate. 



