KEYS TO THE FERNS OF BORNEO 
399 
£. Sori superficial. 
d. Sori in one row on each side 57. 
d*. Sori in plural rows or scattered. 
e. Frond narrowly lanceolate 60. 
e 1 . Frond much broader. 
/. Costa conpicuous 65. 
p. Costa inconspicuous or wanting 66. 
c 1 . Sori slightly immersed. 
d. Frond ovate to round. 
e. Entire or minutely serrate 67. 
gi. Crenate in the lower part 68. 
d 1 . Frond narrowly linear 56. 
cl. Sori deeply immersed. 
d. Sori elongate 64. 
d 1 . Sori round. 
e. Sori in close rows 63. 
Sori mostly far apart 62. 
<ai. Frond simple, entire, membranaceous, veins 
indistinct 69. 
a2. Fronds simple, not deeply lobed, main 
veins or venation as a whole evident. 
b. Sori in one row on each side of costa. 
c. Fertile frond less than 6 mm. wide 70. 
a. Fertile frond about 1 cm. wide 71. 
c 2 . Frond 3-5 cm. wide 72. 
b*. Sori in one row between each hair of 
main veins 73 
(Immature specimens of the subgenus 
Selliguea may seem to belong here.) 
t> 2 . Sori in two regular rows between each 
pair of main veins. 
c. Fronds obtuse 74. 
a. Fronds acute or acuminate. 
d. Pa leas dark, small 75. 
(P. leucophorum , with white spots on 
the upper surface may be looked 
for here.) 
di. Paleae large, pale. 
e. Sori 8 or less in a row 76. 
e 1 . Sori more numerous 77. 
t> 3 . Sori in irregular rows or scattered. 
c. Main veins approaching margin, or 
gradually disappearing. 
d. Frond bearing lime-dots above. 
e. Frond glabrous above 78. 
e l . Frond hairy on both surfaces 79. 
P. subecostatmn. 
P. cur tide ns. 
P. sarawakense. 
P. holophyilutn. 
P. oodes. 
P. dulitense. 
P. tceniophyllum. 
P. revolutum. 
P. stenophyllum. 
P. sori dens. 
P. campyloneuroides. 
P. costulatum. 
P. Treubii. 
P. griffithianum. 
P. platypliyllum . 
P. occultivenium. 
P. rupestre. 
P. triquetrum. 
P. albidopaleatum. 
P. leucophorum. 
P. melanocaulos. 
