CHARACTERS OF TRIBES AND GENERA. 213 



sometimes so deep as to give the indusiam a bi-lobed 

 character, while in others it is scarcely evident and the 

 indusium is then nearly orbicular and thus characteristic of 

 Polystichum. In the " Species Filicum " Lastrea ranks only 

 as a section of Nephrodium ; the author thus not admitting- 

 the difference between anastomose and free venation to be 

 of sufficient generic value to warrant the separation of the 

 two groups of species ; in the section Lastrea 115 species 

 are described, in the " Synopsis " the number is raised to 

 153, of which 65 have Mr. Bakers initials affixed, and in 

 the Appendix 46 species are enumerated, a few of which 

 are for the first time described as new species, but the 

 greater number consists of removals from Avpidium, the 

 specific name being changed in many cases. 



Lastrea as here restricted contains about 100 species, of 

 which 65 have been examined by me in a living state. 



The difference in the position of the sori and forms of the 

 indusium has led to the species being arranged under a 

 dozen or more genera by different authors, none of which 

 have sufficient character to warrant their adoption. 



Sect. 1. Vernation fasciculate, erect or decumbent, in some 

 becoming arbor old (Dryopteris). 



1. OREOPTERIS GROUP. 

 Fronds lanceolate pinnate; pinnce more or less deeply pinnatifid. 



Veins pinnate in the lobes ; venules simple, rarely forked. 



Sp. L. decursivo-pinnata (Kze.) (v v.) (L. decurrens 

 J. Sm.) ; L. exigua (Kze.) ; L. viscosa (/. Sm.) ; L. sancta 

 (Sw.) (v v.). 



OBS. This has hitherto been ranked among nonindusiate 

 Ferns, but having observed small indusia on cultivated 

 plants, I therefore place it here. 



