172 DUBLIN NATXJKA.L HI8T0ET SOCIETY. 



book," has been discarded, but with what utility is to be seen. It is 

 needless to refer to the works of the older botanists — as Ray's '' Synop- 

 sis," Withering's ** Arrangement," Hudson's '* Flora Anglica," Bolton's 

 " Filices Botanicse," and others — for much confusion appears with regard 

 to the species Tunbridgense and its localities, its habits and peculiarities 

 appearing to have been but indifferently known, especially when we 

 find that delicate species quoted by Hay and by Withering as growing 

 amongst pebbles at Cockbush, on the coast of Sussex ; and when we still 

 further refer to that excellent work, '' Species Filicum," of Sir WiUiam 

 Hooker, — we find such numerous affinities and synonyms given as the 

 views of different botanists, at pages 95 and 147, and following, com- 

 pletely perplexing the species Tunbridgense, Wilsoni, and Unilaterale. 

 On such grounds I presume that Mr. Bentham considered the propriety 

 of excluding the two latter, and retaining but one British species, Tun- 

 bridgense. 



There is no tribe of plants to which I have devoted more patient 

 investigation and practical research amid the alpine and subalpine dis- 

 tricts, and the wooded glens and ravines of the western and south- 

 western parts of this country, than to those of the genera Trichomanes 

 and Hymenophyllum. As my remarks are with reference to the latter 

 genus, it is proper that the distinctive characters should be given, and 

 to submit to you, in the recent state, masses of each species. Tt is not 

 necessary to go into detail, when the excellent descriptions, which are 

 well defined, can be readily referred to in Hooker and Arnott's ''British 

 Flora," p. 592; Hooker's ''Species Filicum," vol. i., p. 95; Wilson's 

 "Observations" in Hooker's "Journal of Botany," vol. i., p. 317, and 

 again in " Supplement to English Botany," T. 2686. I may, however, 

 mention that the characters of ^. Tunbridgense, as distinguished from 

 H. Wilsoni, are the broader, almost lanceolate, and more delicate struc- 

 ture of frond, which is of larger size, pinnae are pinnatifid, with nu- 

 merous segments, distichous, or pointing in opposite directions, and flat; 

 the involucres, both in the early stage and in the ripened state of the 

 capsules, broadly ovate, or, more properly, sub-rotundate, • invariably 

 toothed or spinous, and swollen only at the base; colour, pale glossy 

 green. In H. Wilsoni the pinna3 scarcely pinnatified, and with fewer 

 segments than in H. Tunhridgense, the pinnaB unilateral and with the 

 rachis curved in a direction contrary to that of the fructification ; in- 

 volucres numerous, truly ovate, each valve remarkably convex, gibbous 

 or inflated throughout, touching only by their edges, which are entire, 

 and destitute of the toothed or spinous character of the valves which dis- 

 tinguish U. Tunbridgense, a plant of smaller size than Tunbridgense, 

 more rigid, of a strongly reticulated nature, and of a darker or lurid 

 green. 



It is, however, in the distribution of these plants in this country that 

 we find a wide separation. The H. Tunbridgense is decidedly a sub- 

 alpine plant, affecting and assuming a luxuriance of growth only in the 

 moist and sheltered glens and ravines of the south-western parts of this 



