172 CHARACTERS OF TRIBES AND GENERA. 



forming- an acute angle with the mid-rib, their apices pro- 

 longed into a transverse, marginal vein, which becomes 

 the receptacle. Sporangia seated in an extrose slit of the 

 margin which represents an indusium, forming a continuous 

 linear sorus. 



Type. Vittaria lineata, Sm. 



Ulust. Hook and Bauer, Gen. Fil., t. 76, B ; Moore, Ind. 

 Fil., p. 21 ; J. Sm. Brit, and For., fig. 56. 



OBS. This genus is abundantly represented throughout 

 the tropics and sub-tropical regions of both hemispheres, 

 generally growing on trees, their pendulous linear fronds 

 looking like bunches of grass. A considerable number 

 of species have been described by different authors. 

 They differ very little in general appearance, the most 

 obvious difference consisting in the sporangia being seated 

 either in a slit of the margin open exteriorly, or in a groove, 

 formed by the margin being involute. In my " Genera of 

 Ferns," 1841, I separated the species possessing the latter 

 character from Vittaria, and characterised them as a genus 

 under the name of Tceniopsis, which I afterwards found 

 was synonymous with Haplopteris of Presl. Since then I 

 have examined numerous herbarium specimens, and find it 

 difficult in many cases to place them under the respective 

 genera, and as there is no difference in general habit, and 

 no practical advantage gained by the separation, I have re- 

 united them, and given up Tceniopsis as a genus. 



M. Fee has adopted the same course in his memoir of 

 this genus, published in 1852. In that work he describes 

 twenty-five species, eighteen of which are exemplified by 

 figures. In his descriptions he attaches much importance 

 to the fronds being membraneous or coriaceous, and to the 

 mid-rib being more or less evident, but on comparing the 

 figures with one another and with specimens, they appear 



