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TWO CRITICAL FERN GBNERA. 



ANGIOPTERIS, Hoffmann. 



The nearly inexhaustible abundance of forms of the species of the genus 

 Angiopteris, differing only in trifles and united by intermediates but 

 nevertheless showing in typical specimens such differences that 1 cannot 

 refer them all to A. evecta, arborescens (= ongiistifolia) and pruinosa, 

 makes the determination of the species of this genus a puzzle rather more 

 difficult than that of the Cyatheaceae, Dryopteris, etc. 



In my Malayan Ferns I have tried to fix the hitherto described species 

 in a key. This has been not easy at all, since the Buitenzorg Herbarium 

 did not possess correctly named specimens of all those described and 

 furthermore the completeness of the available material left much to be 

 desired. I had to depend principally on the sober diagnoses which were 

 and still are anything but complete. 



Since then several new species have been discovered and described 

 and our Buitenzorg material is now increased so much that, though 

 we have not yet all necessary for an infallible key, ! deemed worth while 

 to study the genus for a second time, as far as regards the Malayan species. 



After careful perusal 1 ajm convinced now that several characteristics, 

 formerly considered as valuable, are futile or nearly so. — F. i. : the shape of 

 the base of the pinnulae, the dimensions, the degree of transparency of the 

 veins and recurrent venules, the shape of the crenatures or serratures of 

 the pinnulae, etc. are of secondary interest. At present I consider more 

 important the presence or absence of a thin layer of wax on the under 

 side of the pinnulae, their common shape with regard to the proportion 

 between length and width, the presence or absence of recurrent venules 

 which run between the true veins from the margin in the direction of the 

 costa, the marginal or intramarginal arrangement of the sori, the kind 

 and colour of the indumentum if more or less present on the rachises 

 and the under side of the costae and veins, the entireness or denticulation 

 of the pinnulae, etc. 



Considering this enumeration of characteristics, treated with more 

 completely in the following key, as a starting point for the limitation of 

 the species, I have tried afresh to fix, with the exception of a few absolutely 

 insufficiently described ones, the other species in the key, which I hope 

 to be in some way fit as a guide in the labyrinth of the (Malayan) species 

 of the genus Angiopteris. 



The wanting species (and perhaps also other well inserted ones) are 

 probably merely deviations of the admitted types. 



