CHARACTERS OF TRIBES AND GENERA. 113 



tomosiug. Receptacles punctiform or oblong linear, pro- 

 duced on the confluence of two or more excurrent arcuate 

 veinlets, terminating in the medial areoles. Sori transverse 

 uniserial, furnished with indusiform peltate scales. 

 Type. Polypodium percussum, Cav. 



Illust. Hook and Bauer, Gen. Fil., t. 18 ; Moore Ind, 

 Fil., p. 62, figs. 1, 2, 3, 4; J. Sm., Ferns, Brit, and 

 For., fig. 12. 



OBS. In my genera of Ferns (1841) I made the genus 

 Pleopeltis, as founded by Humboldt, a section of the genus 

 Phlebodium of R. Brown, but now considering that habit 

 assists to define groups of naturally allied species, and as 

 the species of Phlebodium and those of the present group 

 (Pleopeltis) differ entirely in habit, I deem it best to retain 

 the two as distinct genera. 



In order to show the diiferent views entertained by 

 Pteridologists respecting* the limits of genera, I may here 

 mention that Mr. Moore, in his " Index Filicum," includes 

 under the genus Pleopeltis, the whole, or in some cases 

 part only, of the species of no less than twenty-five genera 

 of authors, of which he makes eight sections, which in 

 most cases differ not only in habit, but also possessing other 

 special characters ; I am, therefore, induced to adopt them 

 as distinct genera. 



The following are the principal species that represent 

 Pleopeltis as here restricted. The greater number are 

 natives of the West Indies and Tropical America, the three 

 first are natives of the Eastern Hemisphere. 



* Fronds smooth, glabrous. (Lepisorus, J. Sm. 1846). 



P. lineare (Thunb.) ; (P. nuda, Hook. Ex. FL, t. 63) (v v.) ; 

 P. excavata (Bory}\ (P. nuda, Hook, and Bauer, Gen. Fil., 

 t.18, non Hool'. Ex. FL} (v v.) 



