ROBINSON: PTERIDOPHYTA OF THE HAWAIIAN ISLANDS 587 
stalked, articulate; veins anastomosing to form a single row of 
areolae on either side of the midvein; sorus upon a linear recep- 
tacle formed by a marginal or intramarginal groove on each side 
of the leaf, non-indusiate. 
Type species: Pteris lineata L. 
VITTARIA RIGIDA Kaulf. Enum. 193. 1824 
TYPE LOCALITY: Oahu. 
DISTRIBUTION: On trees, Polynesia. 
SPECIMENS EXAMINED: Hawaii, Robinson 204 V; 252 V; Oahu, 
Chamisso B; Heller 2054 C; 2532 C: Robinson 152 V; 521 V; 522 
V; Kauai, Kuntze 23039 C; Hawaiian Islands, Baldwin 96 C; 
Lindley C; Wilkes Expedition 3 C; Moore C. 
This is the species wrongly referred by Hillebrand to V. 
elongata Sw. (Hilleb. Fl. Haw. Is. 551. 1888), the type of which is 
from India. In the Indian plants the ventral lip of the sorus is 
shorter than the lateral lip, so that the sporangia are invisible, 
and the leaves are nearly three times as long as those of the 
Hawaiian plants. 
15. FILIX Adans. Fam. Pl. 20. 1763 
Delicate rock ferns, found mainly in temperate regions. Root- 
stock short, erect; leaves clustered, not articulate; sori medial, 
subglobose; indusium attached by a broad base on the inner side, 
free above, soon reflexed. 
Type species: Polypodium bulbiferum L. 
Filix Douglasii (Hook.) comb. nov. 
Cystopteris Douglasit Hook. Sp. Fil. 1: 200. 1846. 
Cystopteris sandwichensis Brack. Fil. U. S. Expl. Exp. 234. 1854. 
TYPE LocALITY: Hawaiian Islands. 
DIsTRIBUTION: Hawaiian Islands. 
ILLUSTRATION: Hook. Cent. Ferns pl. 55. 1854 
SPECIMENS EXAMINED: Hawaii, Wilkes Expedition N, Herb. D. 
C. Eaton; Maui, Wilkes Expedition N; Hillebrand B; Lichtenthaler 
N; Mann & Brigham N; Oahu, Hillebrand B; Hawaiian Islands, 
Baldwin C; Brackenridge N. 
