BRITISH HEPATIC^. 59 



inches in length. Indeed, Dillenius seems to have described it as distinct, in deference 

 to preceding botanists, rather than his own convictions. " Simillima (he writes) est 

 hsec prsecedenti nee ab ea distinguitur, nisi quod folia densius nascantur, et magis 

 imbricatim invicem imponantur, nervum magis protegentia." 



Like most widely-distributed species, Plagiochila asplenioides assumes many forms, 

 dependent for the most part upon differences of soU and exposure. But, as stated by 

 Hooker, " these little differences in the leaves are to be found not only upon plants 

 growing in the same patch, but are even to be met with on the same individual, so that 

 I have not thought it proper to retain, these even as varieties." 



The compact, stunted, glaucous-yellow tufts of ;S minor appear distinct enough on 

 casual examination, but intermediate forms may easily be collected. 



My late friend John NoweU found near Austwick, W. Yorksh,, a very graceful 

 variety, in which the shoots were mostly simple, 2" to 3" long by not more than -j'^" 

 in diameter, with closely-set, small, semi-horizontal leaves, the fronds bearing a close 

 resemblance to those of Saccogyna viticulosa ; whereas Mr. T. Sim has recently forwarded 

 me from Craigendaroch, Aberdeen, specimens (apparently growing on the bark of trees) 

 scarcely half an inch in height, and with shoots less than half a line broad. These 

 probably belong to the var. humilis, Lindg. The leaves are roundish-ovate, entire, or 

 emarginate at the apex, and without any trace of toothing. 



I feel doubtful whether Dr. Taylor, under Flag. Billenii, intended to describe the 

 small form of P. asplenioides or the variety I have named S devexa, which was collected 

 in the west of Ireland, and appears far more deserving to be considered distinct. It 

 grew in dense cushion-like tufts of a pale olive-yellow colour. Shoots sub-compressed, 

 accrescent, curved at the apex (li" by y^"), two or three times innovant-furcate ; 

 leaves broad, deltoid- rotund, closely imbricated, erect; dorsal margin oblique, entire, 

 strongly reflexed,- ventral decurved, and forming with the bases of the opposite leaves 

 a crest, closely ciliate-dentate. Colesule not much exceeding the involucral leaves in 

 length, compressed, oblong, ciliate at the apex. In the compressed, innovant habit, 

 and decurvation of the leaves, so as to form a crest at the back of the shoots, this form 

 reminds us of some foreign species, e. g. P. hifaria or P. retrospectans. 



Pl. IV. Fig. 12. — Plagiochila asplenioides. 1. Barren and fertile shoots natural 

 size. 3. Apeio of fertile shoot x 1 6, showing the involucral leaves, colesule, and capsule 

 covered {as rarely happens) by the calyptra. 3. Stem-leaf magnified. 4, Leaf-cells x 250. 

 6. Perigonial leaf enclosing antheridia. 6. Antheridium magnified. 7. Pa/rtofapex 

 of leaf y. 120. 



3. Plagiochila spinulosa, Dumort. 



Pl. IY. Fig. 14. 



Stolons creeping, radiculose; shoots densely tufted, dichoto- 

 mously ramose ; leaves approximate, semi-vertical, erecto-patent, 

 deltoid-ovate to obovate, dorsal margin strongly decurrent, re- 

 flexed, entire, apex 2-3-dentate, ventral margin irregularly toothed ; 

 colesule urceolate, compressed, bilabiate, ciliate-dentate. 



Jimgermannia spinulosa, Dicks. Gryp. Fasc. ii. p. 14 (1790); E. Bot. t. 2228; 

 Hook. Br. Jung. p. 9, t. 14; HUben. Hep. Germ. p. 113 ; N. ab B. Leberm. Eur. i. 

 p. 157 ii. p. 423; Hook, Bk FJ. v. i, p. 103; Mackay, Fl. Hibern. ii. p. 58, n. 10. 



