252 CHAEACTERS OF TRIBES AND GENERA. 



dium pruinatum, by later authors it has been referred to 

 Alsophila, under which genus it stands in the " Species 

 Filicum," but it differs from the true species of that genus 

 in having deltoid multifid fronds. The only character 

 that gives it a claim to rank as a species of that genus is 

 its arborescent stem, and criniferous sori, which, in some 

 specimens the latter character is scarcely evident ; the 

 stem also differs from true AlsopJiila in being densely 

 laniferous, indeed, if it was not for its arboroid stem I 

 would have no hesitation in placing it under Phegopteris, as 

 an ally to Phegopteris lachnopoda. Presl has considered it 

 worthy of being raised to the rank of a distinct genus, 

 which, in order to mark its peculiarities I adopt, and, 

 with Trichopteris and Amphidesmium, view it as an aberrant 

 genus of this tribe. 



Sp. L. pruinata (Presl} (v v.) (Polypodium griseum, Sclik. 

 FiL, t. 25.) 



135. AMPHIDESMIUM, Schott. (1834). 

 Metaxya, Presl., 1836; AlsopJiila, Hook. Sp. Fil. 



Vernation fasciculate, erect, arboreous, criniferous. Fronds 

 pinnate, 4 to 6 feet long, smooth, glossy ; pinnaD 6 to 12 

 inches long, linear lanceolate, acuminate, serrated towards 

 the apex, adherent to the rachis. Veins simple or rarely 

 forked near their base, parallel, patent. Sori punctiform, 

 lateral, basal, transverse uniserial near the costa, as also 

 scattered with two or more sori on some of the venules, 

 densely furnished with criniferous hairs. 



Type. Polypodium llechnoides, Rich. (P. rostratum, Humb.} 



Illust. Hook, and Bauer. Gen. Fil., t. 42 B ; Moore Ind. 

 Fil., p. 86 A ; J. Sm. Ferns Brit, and For., fig. 83. 



OBS. This genus is founded on a solitary species, a native 



