DITBLIN NATUBAL HJ8T0BT SOCIETY. 193 



Dr. E. Peeceval Wright remarked that Dr. Kinahan had said 

 nothing about the herbarium specimens exhibiting variations in the 

 toothing of the involucre. 



Dr. Kinahan intended these to be included under his remarks con- 

 cerning the intermediate Australian specimen ; a personal examination 

 of them might lead him to very different conclusions as to their species 

 from Dr. Wright's. 



The President rose, and said that he should offer but few remarks, 

 as he had given so fully his views upon the distinctive characters of the 

 two ferns in his papers at the previous meetings, and that recapitulation 

 was not again necessary. He should confine his observations to the 

 fern family. He was well aware that specimens oi Hymenophyllum Tun- 

 hridgense are in the Hookerian Herbarium from the Oregon Mountains and 

 from Tasmania, and described in the ** Species Filicum" as having the 

 involucres nearly entire, and scarcely distinguishable from those of H. 

 WiUoni; yet so little dependence can be placed on the examination of spe- 

 cimens collected at remote periods, and which are only seen in a dried and 

 shrivelled condition, that the authority of such specimens as to the pas- 

 sage into intermediate states can have but small pretensions in setting 

 aside the distinctive forms shown in all gradations of growth and of fruc- 

 tification by our British species. Botanists have had ample experience of 

 the difficulties of retaining in their collections the true state of the ori- 

 ginal and recent form of a plant where the essential characters of the 

 recent state are so fugacious as to be altogether lost in Herbaria. On 

 reference to specimens oiHymenophyllumTunhridgense, many years since 

 collected, and but imperfectly dried in bad paper, the fronds have so lost 

 their colour, and the involucres, from undue compression, and perhaps 

 the careless shifting* of papers, that they present but faint outlines of 

 their true habit and distinction. Thus contracted involucres and almost 

 obliterated serrations abound, or spinulose characteristics alter and de- 

 ceive the examination. In some cases the imperfect state or develop- 

 ment of the fertile venules may lead to many misconceptions of the 

 character of a genus, more especially when the true manner in which 

 the sporangia are produced cannot be detected. In the examination of 

 the plants of an herbarium, with reference to the inconstancy of fructi- 

 fication as a determinate characteristic, such views cannot as a general 

 principle be maintained, for the specimens in an herbarium, from im- 

 perfect development when collected, or from the process of drying, may 

 not present their determinate characteristics, as we see in the genus 

 Pleocnemia, which had been considered, ft^m the apparent absence of 

 a special indusium, to have been a Polypodium ; but the examination of 

 a perfect specimen had determined its character as belonging to Aspidieae. 

 The fugacious character of the indusium, and its disappearance in ad- 

 vanced age or mature state of the plant, have too frequently caused 

 plants to be described as belonging to Polypodieae, when they are really 

 true Aspidieo). Mr. J. Smith, of the Royal Botanic Garden, Kew, who 

 has given many highly scientific and valuable notes on the genera of 

 ferns, has, by a systematic examination of their states under cultivation, 

 as well as from careful comparisons of collections made in different parts 



