LASTREA. 209 



GENUS V. 



LASTREA. Presl. 



A GEXUs having herbaceous or coriaceous fronds. 



Caudex creeping, erect, or decumbent, short and stout. 



The fertile fronds are sometimes slightly contracted. 



Veins simple, forked, or pinnate from a central costa; venules 

 free, the anterior fertile, and occasionally others. 



Sori globose, and having an indusium; the receptacles usually 

 medial. TTie distinction consists in the rounded reniform 

 indusium, and in its position, being attached at the basal sinus. 



There are, according to Moore, eight -well-marked British 

 species, namely, — L. thelypteris, montana, JiUx-mas, remota, 

 rigida, cristata, dilatata, and cemida. 



As we proceed I think it will be shewn that more than 

 this number of species exist in our island, and that, as an 

 instance, in what we have considered hitherto as Lastrea 

 filiz-mas, we have in reality embraced three distinct species, 

 which Mr. Wollaston proposes shall henceforth bear their 

 specific rank under the names of Lastrea Jilix-mas, Presl ; L. 

 pseudo-mas, Wollaston; and L. j^f'ojiinjna, Wollaston. 



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