27 



A vast amount of labour and ingenuity has been expended on 

 the consideration of these two ferns (L. spinulosa and L. dilatata) 

 and their varieties, with the view of establishing decided limits 

 between the latter, or of elevating the most marked deviations 

 from what has been agreed upon as the normal form, to the rank of 

 species. The result has not been at all satisfactory ; that which was 

 a point of dispute a generation or two back, still remains so ; and 

 although botanists freely discuss opinions with each other, and 

 maintain or controvert according to present conviction, every new 

 work, nay, every new edition proves the instability of their own ; 

 the species of one day becomes the variety of another, the variety 

 of yesterday may be the species of the morrow, or it may be dis- 

 carded altogether. This has been the case over and over again 

 with the ferns before us. Being of wide distribution, and appa- 

 rently indifferent, so far as mere capability of growth is concerned, 

 to soil, elevation, and exposure, they assume a diversity of aspect 

 according to circumstances : to what extent the influence of such 

 causes may have contributed to the multiplication of supposed 

 species in this and other genera, future observation must decide ; 

 the whole genus Lophodium of Newman, a well-marked group 

 among British ferns, may be implicated. 



On these grounds, added to the uncertainty of definition afforded 

 by characters too slight and variable to be depended upon, I leave 

 the alleged varieties of L. dilatata to be determined by the fancy of 

 the observer. 



LASTREA F<ENISECII. Recurved prickly-toothed Fern. Hay- 

 scented Fern. TAB. XIV. 



Fronds curved, elongate- triangular, sub trip innate : pinnules 

 pinnate or deeply pinnatifid, with serrate spinose-mucronate lobes. 

 Indusium jagged at the edge. Scales of the rachis narrow lan- 

 ceolate, laciniate, pale. 



Lastrea foenisecii, Watson. Babington, Man. Moore, Handb. As- 

 pidium recurvum, Bree. A. dilatatum, var. concavum, Ba- 

 bington. A. spinulosum var., Hooker and Arnott. Lophodium 

 foenisecii, Newman, Hist. Brit. Ferns, 135 (the figure far from 

 characteristic). 



This fern, though rather widely distributed in the British islands, 

 ia generally regarded as originally a wanderer from the Azores, or 

 other Atlantic groups ; in corroboration of which opinion we find 

 it most abundant in the south-western counties of England and 

 Ireland, the situations toward which it would naturally be drifted 

 by the tidal wave, or where its sporules would be wafted by the 

 prevalent south-westerly winds. That it is among the later addi- 



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