100 CHARACTERS OF TRIBES AND GENERA. 



Veins compound anastomosing ; primary veins costaeform, 

 elevated or internal, generally flexuose, in some immersed. 

 Receptacles compital, superficial. Sori punctiform, or by 

 confluence oblong or linear, irregular or partially obliquely 

 1 $ serial. 



Type. Polpodium normale, Don. 



Illust. Hook, and Bauer, Gen. Fil. t. 109, B. Hook, and 

 Grev. Ic. Fil. t. 65. J. Sm. Ferns, Brit, and For., fig. 24. 



OBS. The species of this genus agree with Phymatodes 

 and Pleuridium, but differ in the nature of the caudex, and 

 the fronds of the greater number of the species being thin 

 and flaccid, as also in the irregular disposition of the sori. 

 With Selliguea it is connected through C. membranacea, 

 in which the punctiform sori are united, forming linear 

 oblique sori, which character has led the author of the 

 " Species Filicum " to place it in Gymnogramma. The 

 irregular arrangement of the sori is also conspicuous in 

 G. Samarense ; in some fronds the sori are punctiform, 

 while in others the receptacles unite, forming linear, or 

 even transverse continuous sori, and also at the same time 

 punctiform sori. This apparently double character induced 

 me to elevate this species to the rank of a genus, which in 

 1841 I characterised under the name of Diblemma, but 

 later observations have shown me that it cannot with pro- 

 priety be separated from the present group. 



The genus consists of about sixteen species, all natives of 

 the Eastern Hemisphere, extending from Western Tropical 

 Africa through India, the Malayan Islands, China, Australia, 

 and Polynesian Islands. 



* Fronds simple. 



Sp. C. zosterfflforme (Wall.); C. normale (Don.) (Poly, 

 podium longifrons, Wall.) ; C. Ovata (Wall.) ; C. membra- 



