EUPTERIS AQUILINA. 25 



Presl, in his 'Tentamen Pteridographise ' (p. 143), has revised 

 and divided the genus Pteris, referring the present species to 

 Bernhardi's genus AUosorus : but in this genus he has included 

 species which scarcely possess a character in common : and, 

 moreover, the Allosori aquilini, to which division of the genus 

 the brakes is referred, constitute the third and not the typical 

 division of the genus, which properly includes the AUosorus 

 crispus, a very distinct and different plant. It therefore ap- 

 peared necessary to institute a new genus for the reception of 

 the Allosori aquilini of Presl. 



The brakes is the " Filix femina " of all the older authors, 

 and the transfer of that trivial name to another species was 

 made by Linneus, who gave the plant now under consideration 

 its present appellation of aquilina. However unadvisable the 

 change may have been at the time, it has been generally adopted 

 by subsequent botanists. 



Figures invariably fail to give a correct idea of this fern, from 

 the difficulty of reducing it to the requisite size. 



The geographical range of this fern can scarcely be ascer- 

 tained, until we are agreed upon the latitude to be allowed for 

 variation in a species. Mr. Houlston, of Kew, one of our best 

 pteridologists, associates under the name of aquilina cognate 

 forms from all parts of the world. Every country of Europe 

 furnishes the normal form, as Pteris aquilina ; then we have 

 three Russian species, P. nudicauHs, P. brevipes and P. taurica; 

 Africa has its P. lanuginosa and P. capensis ; Nepaul its P. re- 

 curvata; central India its P. latiuscula ; Ceylon its P. lanugino- 

 sa ; New Zealand its P. esculenta ; the Sandwich Islands P. 

 decomposita ; North America its P. caudata ; South America 

 P. arachnoidea ; the West Indies a form allied to P. caudata ; 

 the Cape de Verde Islands, the Azores, the Canaries, and 

 Madeira, different forms, all known by the name of P. aquilina. 

 Although the whole of these may be referred, without doubt, 

 to the genus Eupteris, I am not willing to unite them into one 

 species, on account of the extreme discrepancy in the circum- 

 scription, detail, and general appearance of the frond. 



E 



