294 CHARACTERS OF TRIBES AND GENERA. 



allies, but are distinguished by the lower pair of venules of 

 each fascicle anastomosing, forming a row of elongated 

 transverse areoles on each side of the mid-rib, which 

 character I originally considered to be only a simple state 

 of Litobrochia ; I, however, now deem it best to adopt it 

 as a transition genus between Pteris and Litobrochia. 



Sp. C. nemoralis (Willd.} (v v.) ; C. biaurita, (Linn.) 

 (v v.) ; C. geminata (Agardh.) 



Natives of the tropics of the Eastern and Western 

 hemispheres. No less than thirty-eight synonyms are 

 placed under C. biaurita by Dr. C. Luerssen. 



168. HISTIOPTERIS, Affardh. (1839). 

 Pteris sp. auct., Hook. Sp. Fil. 



Vernation uniserial, distant ; sarmentum elongated, 

 generally epigeous and hirsute squamose. Fronds 1 to 8 

 feet high, or sometimes scandent, and then ascending to 

 15 or 18 feet, bi-tripinnate, smooth or glaucous beneath; 

 primary pinnae and pinnules generally horizontally patent, 

 always opposite and sessile, the lower pair of pinnules of 

 each pinnae often short and stipuliform, ultimate pinnules or 

 segments entire, sinuose or pinnatifid. Veins anastomosed, 

 or sometimes free. Receptacles transverse, continuous 

 across the anastomoses of the venules, forming a linear, 

 marginal sorus, furnished with an exterior attached, linear 

 indusium. 



Type. Pteris vespertilionis, Labill. 



Illust. Mett. Fil. Hort. Bot. Lips., p. 59, t. 14. 



OBS. This genus consists of a few species of peculiar 

 habit, differing from Litobrochia in the same manner that 

 Ornithopteris does from Pteris, in this case, as in others, 

 habit being the most obvious distinction. 



