CHARACTERS OP TRIBES AND GENERA. 345 



Hymenophyllacece have a wide geographical range, 

 abounding in the tropical regions of America and the West 

 Indian Islands, in India, the Islands of the Indian and 

 Pacific Oceans, and extending as far as New Zealand and 

 Lord Auckland's Islands in the southern hemisphere, and 

 Norway and the Faroe Islands in the northern ; but very 

 sparingly found on the African continent, They love 

 shade and moisture, many being epiphytal and clothing 

 trees like moss, or growing in shady ravines or caves ; 

 but the same species often occurs under different influences, 

 and consequently assumes different appearances, which has 

 led to an unnecessary increase in the specific nomenclature. 

 The number of species varies according to the views held 

 by different authors, 1 72 are described in the " Species 

 Filicum," and are nearly equally divided between the two 

 genera, Hymenophyllum and Tricho manes, which in the 

 " Synopsis " are reduced to 149. 



This, however, falls far short of the number given by 

 Dr. Van Den Bosch, who, in his " Synopsis Hymenophylla- 

 cearum," enumerates no less than 802 species, as already 

 shown at page 31. 



199. HYMENOPHYLLUM, Sm. (1793). 



Vernation uniserial and sarmentose. Fronds varying 

 from simple to decompound multifid, membranaceous and 

 pellucid, smooth, or bearing simple forked or stellate hairs. 

 Veins simple or forked, free. Sori terminal. Indusium 

 urceolate, bilabiate, or bivalved. Receptacle short, included 

 within the indusium. 



Type. Hymenophyllum Tunbridgense, Sm. 

 Illust. Hook, and Bauer Gen. Fil., t. 32 ; Moore Ind. 

 Fil., p. 90, A. ; J. Sm. Ferns Brit, and For., fig. 137; 

 Hook. Syn. Fil., t. 2, fig. 16. 



