568 PLANTjE javanic^ rakioees. 



midrib, in which there is one only, and that terminating 

 the single vein exactly as in Phlebodium, into which this 

 group passes by species having the habit of Cyrtophlebium, 

 but with fronds so narrow, that they are reduced to the 

 lowest areolae, and consequently agree in character with 

 Phlebodium. 



An arrangement of veins and of sori analogous to Cyrto- 

 phlebium exists in the real species of Ctclophorus or 

 Niphobolus, none of which are natives of America : in all 

 these the secondary veins are straight and parallel, instead 

 of being arched ; they are also given off at an angle more 

 or less acute from the primary parallel veins, which they 

 connect ; and the tertiary or ultimate branches originating 

 only on the upper side 'of each secondary vein are parallel 

 with each other, more than three in number, and all of 

 them bearing terminating sori. 



An extensive and strictly natural group may be next 

 noticed, though it cannot be considered nearly akin either 

 to any of the preceding sections or to the principal part of 

 that which follows. 



This group or subgenus, the Lastrea of M. Bory, whose 

 fronds are either bipinnatifid or simply pinnate, is chiefly 

 intra tropical. Its character consists in the secondary veins 

 of the pinnate, and the only veins of the segments of the 

 bipinnatifid fronds being perfectly simple and parallel, with 

 one known exception reaching the margin of the segment, 

 or in the pinnate species uniting with the corresponding 

 vein, and each bearing a lateral sorus, generally about the 

 middle, in some cases near the base, and in a few others 

 proceeding from the base itself. 



The closest affinity of Lastrea is not to any group of 

 Polypodiura, but to that section of Gymnogramraa, the 

 division of whose fronds, and the disposition of veins, are 

 exactly similar, and in which the sori form very short lines 

 of like origin. As the only distinction therefore consists 

 in a difference, generally very slight, in the form of the 

 sorus, it appears to me (and I)r. Blume has made a similar 

 remark) that these two tribes cannot be generically sepa- 

 rated, especially as species belonging to both agree in 



