194 DTJBLIN NATURAL HI8T0EY SOCIETT. 



of the globe, proved many errors existing among the named specimens 

 of collectors, as is strikingly shown in the genus Stenosemia. In Sir 

 William J. Hooker's herbarium, the most extensive in the world, there 

 still must exist many doubts as to true generic characters and specific 

 distinctions and affinities, from the want of examination of recent spe- 

 cimens. Then, upon what grounds are the distinctive characters of the 

 specific forms of Hymenophyllum Tunhridgense and H. Wihoni to be set 

 aside? Upon mere assertion, and upon the appearance presented by 

 some dried specimens fix)m Australia of //. Timhridgense, of having the 

 involucres nearly entire. Perfect and recent plants of both species of 

 this country have been exhibited to this meeting. Where are the spe- 

 cimens in contradiction, and which are to support the views of those 

 who maintain the unity of the species ? The two species are admitted 

 as perfectly distinct by the highest scientific as well as the most prac- 

 tical British botanists, and no departure can be shown from the cha- 

 racters hitherto described of those species in any locality in the British 

 Isles and in this country. Then, why introduce such confusion into 

 British Botany ? It is not upon the authority of even Continental or 

 European specimens, but upon those from xVustralia. When doubts 

 exist, the forms even in exotic herbaria should not be admitted until sa- 

 tisfactorily proved by examination in the recent state, and of aspect under 

 cultivation. In conclusion, I shall not mention the names of several 

 scientific botanists and experienced travellers who have communicated 

 with me in corroboration of my views. It is quite sufficient to give the 

 name of one whose high scientific position, whose valuable writings, and 

 w^hose extensive practical observations place his authority unquestion- 

 able, — Sir William Jackson Hooker, — whose letter I now lay before 

 you: — 



" Royal Gardens, Kew, April 18, 1859. 

 '* My deae Me. Andeews, — Many thanks for your interesting com- 

 munication respecting the two Hymenophylla — lunhridgense and Wil- 

 8oni — and still more for the charming patches of the two plants, which 

 are very acceptacle to oui* Garden, — and which, I must honestly confess, 

 confirm my views, which I have, I believe, invariably expressed, that 

 our two plants are perfectly distinct. It is true the fronds are very si- 

 milar, but I find such characters in the involucres, and they afiford the 

 most tangible characters throughout the genus, that I cannot fancy the 

 one passing into the other — the texture of the involucres, the form of 

 the valves always firmer, thicker, and more gibbous (almost semi-glo- 

 bose) ; in JI. Wilsoni the direction of the involucre is difierent. In 

 H. Tunhridgense it lies in the same plane with the fronds; in JI. Wilsoni 

 it is less sessile, and diverges with a curvature /7-ow the frond (as well 

 represented in '* English Botany," Supplement Table, 2686 : compare with 

 H. Tunhridgense, "English Botany," 1. 162). Again, though li. Wilsoni 

 has the valves of the involucres of a firmer texture, when the y expand 

 in age they are more convex in form, the sides turning up morc, so that 

 the valves almost become semi-cylindrical. In H. Tunhridgense the tex- 

 ture of the valves is scarcely different from that of the frond, yet they 

 retain in age, and when expanded, morc of their original flattened or 



