CHAEACTEES OF TEIBES AND GENEEA. 329 



side, their apices combined by a transverse, continuous 

 marginal vein. Sari unilateral. Indusium plane, free 

 exteriorly. 



Type. Asplenium nidus, Linn. 



Illust. Hook, and Bauer, Gen. Fil., t. 113 B. ; Moore, 

 Ind. Fil., p. 37 B. ; J. Sm., Ferns, Brit, and For., 

 fig. 113. 



OBS. This genus is distinguished from other simple- 

 fronded Aspl&nice by the apices of the parallel venules being 

 combined by a continuous marginal vein ; it has a wide 

 geographical range, being represented throughout India, 

 the Malayan peninsula and islands, Southern China, Philip- 

 pine, Sandwich, and other islands of the Pacific Ocean, 

 extending to Australia and Norfolk Island in the south, 

 and Japan in the north. 



In Seemann's " Botany of the Voyage of the Herald " 

 it is there recorded to have been found in one or two 

 localities on the Pacific side of the continent of America, 

 but this seems to be a mistake, as the Hookerian herba- 

 rium contains no specimen of the genus from the American 

 continent. 



The simple form of the fronds does not afford much 

 variety as regards difference that can well be explained in 

 words, yet they vary very much in size and texture, which 

 in some instances seem to be normal to the special localities, 

 and which gives the semblance to there being a number of 

 distinct species, thirteen being enumerated by Fee, which 

 in the '' Species Filicum " are reduced to seven ; even this 

 is more than can be satisfactorily determined by herbarium 

 specimens only. The cultivated examples of four forms 

 known to me, although difficult to recog'nise as distinct 

 when put in the herbarium, are, however, readily seen to 

 be distinct species in the garden, and it is probable that 



