CHRISTENSEN, ON SOME SPECIES OF FERNS. 21 
tuse apex. Margins of frond sinuato-cris- 
pate, not plicate. 
3. H. tortuosum Hk. & Grev. 
2. Valves acute, entire. Frond distinctly 
plicate. 
4. H. dichotomum Cav. 
b. Frond plane. Valves more or less acute, den- 
tato-ciliate. 
5. H. magellanicum Willd. 
B. Stipe wingless, pilose. Frond plane. 
6. H. dentatum Cav. 
The species 3, 4 and 5 are in general habit fully identi- 
eal, and it may be a question, if the differential characters 
mentioned in the key can be relied upon as being of real 
specific value. PHILIPPI has described three species, which 
seem to connect the three species with each another. The 
main characters of these forms are according to the descrip- 
tions: 
Hym. Krauseanum Phil. Linnaea 30: 208. 
Frond plane; valves entire. 
Hym. quadrifidum Phil. l. c. . 
Frond plicate; valves entire, bifid. 
Trichomanes Beckeri Krause; Phil. Linnaea 33: 305. 
Frond plicate; valves ciliato-spinose, receptacle much 
exserted. 
To the first of these I refer a specimen from Isla Huafo, 
SKOTTSBERG n:r 378, 25. 7. 1908. It has the plane frond of 
H. magellanicum but otherwise, especially in its indusial cha- 
racters, it agrees with H. dichotomum, to which species I re- 
fer it as var. Krauseana (Phil.). In the mature sori the val- 
ves are separated from the inflated, cup-shaped base of the 
indusium, beyond which the receptacle is much protruding. 
I suspect Trichomanes Beckeri Krause to be a corresponding 
form either of H. dichotomum or of H. tortuosum. H. quadri- 
fidum Phil, which the author was inclined to consider be- 
longing to a separate genus Tetralasma (this name omitted 
in my Index), because its quadrifid indusium, is scarcely 
different from H. dichotomum, and the proposed new genus 
is synonymons with Piychophyllum Presl (see PRESL’s figure, 
Hym. tab. XI E.). 
