DUBLIK VATUBAL HI8T0BT 80CIBTT. 171 



[William Andrews, M. R. I. A., President, read the following paper 

 on Friday, March 4 (vide p. 374) — 



ON THE DISTINCTIVE HABITS OP BBITISH HTMENOPHTLLITM. 



In the examination of any subject of interest in the Natural Sciences, 

 whether in relation to Botany or Zoology, we are ever guided by those 

 characteristics that determine with some degree of accuracy generic and 

 specific differences : hence anatomical structure and physiological deduc- 

 tions are, through their minute investigation, the surest means of arriv- 

 ing at definite and truthful results. In the former science the application 

 of the rules of morphology may restrain the extent to which laws can 

 assign limits of variation to a given species. I have been led to offer 

 a few remarks this evening, from a perusal of the "Handbook of the 

 Flowering Plants and Ferns of the British Isles," by George Bentham, 

 Esq., F. L. S., recently published, in which he has reduced the plants 

 indicated as British in the late works of Hooker and Amott's "British 

 Flora," and in Babington's "Manual," by the suppression of presumed 

 erroneously introduced species, by the number of 286 in the former work, 

 and 423 in the latter. I have ever advocated in this Society that the 

 young naturalist had, in the advanced state of science, greater opportu- 

 nities, and that more merit would result from an investigation of a revi- 

 sion and correction of our zoological and botanical nomenclatures than 

 in new discoveries or additions to our Fauna and Flora. Although it is 

 extremely difficult to form opinions as to the limitation of species, yet I 

 fully concur in the views of those who consider that species have been 

 multiplied far beyond their due limits. Still, extremes in either sense are 

 questionable, for even the non-existence of distinct species has been 

 asserted. I am aware that from distribution, locality, or peculiar cir- 

 cumstances of habitat of plants, much variation and depaiinre from the 

 normal or typical form may be seen, and those characters maintained 

 even under cultivation, and continued through seedlings ; yet such can- 

 not constitute specific differences, when no essential departure can be 

 shown from the principles of fructification which marked the original 

 form. 



My observations on Mr. Bentham* s work (a gentleman whose high 

 scientific position and botanical zeal deserve our admiration and respect) 

 are solely with reference to the plants of this countrj'^, wherein omissions 

 and alterations of the hitherto recorded lists of the flowering plants and 

 ferns of Ireland occur. My present remarks wiU be confined to the 

 genus Hymenophyllum, a family the most beautiful and minute of our 

 native Ferns, when seen in all their luxuriance of growth in the primeval 

 woods, or on the rocks of the Alpine districts of the wild and moist 

 atmosphere which characterizes the south-western parts of this country, 

 their beautiful and singularly delicate fronds extensively spread like a 

 velvet carpet of the most rich and verdant hue. Of this genus we have two 

 well recorded and described species, Hymenophyllum Ihnbridyense and JZ 

 Wihoni ; but the latter, in Mr. Bentham's recently published " Hand- 



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