MAXON—STUDIES OF TROPICAL AMERICAN FERNS. 587 
thyssanolevis. The confusion of locality data for certain of Linden’s specimens 
has already been mentioned.’ Fée’s illustration well represents this species. 
(2) Polypodium aspidiolepis Baker. An examination of ample material of 
this form, which seems to be restricted to Costa Rica, shows that not only 
in general proportions and vestiture but even in the minute stucture of its 
rhizome and lamina scales it is exactly P. thyssanolepis. It occurs with the 
ordinary form of the species and differs from that only in its bipinnatifid con- 
dition, the dissection of the pinnz being accompanied by a partial loss of 
areolation, as might be looked for. This relationship was recognized by Christ, 
who fully described this state from Costa Rica as P. thyssanolepis var. bipin- 
natifidum,’ calling attention to P. aspidiolepis as being “ according to descrip- 
tion, an analogous plant.” 
(3) Polipodium purpusii Christ. This was described from specimens culti- 
vated in Darmstadt by Dr. J. A. Purpus, the original plants having been col- 
lected at Pachuca, Mexico, by Dr. C. A. Purpus, in 1904, and is known to the 
writer from several fronds courteously fowarded to Washington by the former. 
These represent merely a juvenile condition of typical P. thyssanolepis. 
The identity of P. lanuginosum Nees, mentioned by Christensen as a doubtful 
synonym of P. thyssanolepis, is problematical. It is not even apparent that 
it belongs in Polypodium. Moreover, the determination is not of great im- 
portance, since, as noted in the synonymy, the species name lanuginosum would 
be unavailable for use in this connection. 
Polypodium thyssanolepis, though variable in size, is not readily confused 
with other species. Christensen ascribes it to Cuba, but that record probably 
results from the doubtful data of Linden’s type of P. rhagadiolepis. The fol- 
lowing specimens are in the U. S. National Herbarium: 
Arizona: Conservatory Canyon, Huachuca Mountains, July to September, 
1882, Lemmon. Ramsey Canyon, Huachuca Mountains, August 23, 
1910, Goodding 761. 
Mexico: Cold cliffs, rocky hills near Chihuahua, Pringle 443. Pachuca, 
Hidalgo, Orcutt 3933; cultivated specimens, originally from the same 
lecality, Purpus (type’ collection of P. purpusii). Near El Salto, Hi- 
dalgo, on calcareous cliffs, Rose 7057. Near Ixmiquilpan, Hidalgo, 
Rose 9042. Barranca de l’Alseseea, Puebla, June 12, 1912, Arséne. 
Alta Suz, Puebla, Purpus 2688. Region of San Luis Potosf, alt. 1.600 
to 2,400 meters, Parry & Palmer 971. Santiago Papasquiaro, Durango, 
Palmer 458 in 1896. Near Durango, Palmer 885 in 1896. Otinapa, 
Durango, Palmer 359 in 1906. Orizaba, Veracruz, Hitchcock; Seaton 
99; J. G. Smith 82. Near Jalapa, Veracruz, Rose 6361. Tonila, 
Colima, Jones 506. Amecameca, Purpus 1825, Rio Blanco, near 
Guadalajara, Jalisco, Palmer 730 in 1886; Rose 7503. Sierra Madre, 
west of Bolafios, Jalisco, Rose 3710. Near Chapala, Jalisco, Rose 7670, 
7398. Near Plateado, Zacatecas, Rose 2797. Sierra Madre, Zacatecas, 
Fose 2399. Several localities in Valley of Mexico, /. G. Schaffner 63; 
Bourgeau 254, 2780; Orcutt 3647; Rose 6468, 8274, 9462, 11036. Eslaba, 
Federal District, alt. 2,400 meters, Pringle 11801. Toluca, Mexico, 
Pose 6797. Tultenango, Mexico, Rose 7856. Las Naranjas and San 
Luis, Oaxaca, Purpus 3154. 
GUATEMALA: Depart. Huehuetenango, C. € EH. Seler 2607. 
Costs Rica: Cartago, alt. 1,300 meters, Alfaro (J. D. Smith, no. 6955) ; 
Beyer 21; Biolley 82; Biolley 85 (bipinnatifid form). San Rafael de 
Cartago, alt. 1,600 meters, Pittier 9721 (including bipinnatifid form). 
*Pages 563, 564. 
? Bull. Soc. Bot. Belg. 35: 223. 1896. 
