MAXON STUDIES OF TROPICA!, AMERICAN FERNS. 9 



excised below; pinnse very densely covered below with appressed imbricate tawny 

 scales, these very long-attenuate from a small subovate fimbriate darker-centered 

 base, wholly concealing the leaf-tissue, above hnary with scattered whitish ciliate 

 scales, these filiform from a deeply stellate roundish base; venation distinctly and 

 typically goniophlobioid, a single row of narrow oblique areoles upon either side of 

 the slender blackish costa, deeply immersed and otherwise wholly concealed by the 

 scales; sori small, inconspicuous, 20 to 30 or more pairs, inframedial, terminal upon 

 the single included veinlets. 



Type in the U. S. National Herbarium, no. 820189, collected from rocks and the 

 trunks of oaks near Santa Rosa, Baja Verapaz, Guatemala, altitude about l,(i00 meters, 

 by Baron II. von Tiirckheim, no. II. 1607, December, 1906. Other specimens from 

 the same locality sent later under the same number were gathered in March, 1908. 



The present is only one of a considerable number of more or less closely allied trop- 

 ical American species, several of them of rather wide distribution, and most of them 

 commonly misundertsood. It is related to the ( osta Rican P. myriolepis Christ, 

 which has been most injudiciously reduced to P. shinneri Hook. The last, of which 

 P. bernouillii Baker is a true synonym, was described and figured upon Guatemalan 

 specimens and appears to extend only northward into Mexico. The- distinctive 

 characters of these and of several others, some of them as yet undescribed, will be 

 indicated in the next paper of this series. 



Phlebodium pulvinatum (Link) J. Sm. 



II. 1881. Coban, altitude 1,350 meters, June, 1907. 



Polypodium biauritum Maxon, sp. nov. 



Fronds rigid, about 90 cm. long, borne about 1.5 cm. apart; rhizome repent, 8 to 10 

 mm. thick, covered closely with small triangular-ovate centrally attached yellowish 

 scales, these dark brown at the short apex; stipe stout, 33 to 37 cm. long, about 2.5 

 mm. in diameter, yellowish to yellowish brown, glabrescent; lamina elongate Iri- 

 angular-ovate, about 60 cm. long, 34 to 30 cm. broad in the lower half, comprising 

 about 25 pairs of patent simple, mostly subopposite, linear-ligulate pinnae; lowermost 

 pinme subcordate at the base, mostly free at the inferior basal margin and overlap- 

 ping the rachis, partially adnate at the superior basal margin, the middle pinme 

 slightly longer, partially adnate below, wholly so above, the upper pinn;e gradually 

 reduced, adnate and somewhat, dilatate at the base, finally forming a deeply serrate 

 elongate caudate apex about 1 cm. long; characteristic pinna? of the lower third of 

 the lamina 10 to 20 cm. long, 15 to 18 mm. broad, dull greenish, translucent, fragile, 

 papyraceo-herbaoeous, broadest in the basal third, tapering thence very gradually 

 toward the somewhat attenuate subacute apex, at the base usually more or less 

 constricted (especially below) with a small rounded auricle both above and below, 

 the margins otherwise irregularly, but invariably cenate, ciliate; rachis and upper sur- 

 face of the midveins conspicuously pubescent with very close-set light yellowish join t ed 

 glandular hairs, the midvein below less noticeably pubescent, the veins glabrate; 

 sori uniserial, superficial, about 45 to 50 pairs, considerably nearer the margin than 

 the midvein, borne at the extremity of the first anterior branch of the dark mostly 

 twice or thrice forked oblique evident veins. 



Type in the U. S. National Herbarium, no. 820213, collected in the forest between 

 Purulha and Panzal, Baja Verapaz, Guatemala, at an altitude of 1,500 meters, by 

 Baron H. von Tiirckheim, no. II. 1688, April, 1907. Imperfect specimens collected 

 in the District of Cordoba, State of Vera Cruz, Mexico, by Hugo Fink (no. 70), are 

 apparently a smaller state of the same species. 



Polypodium biauritum has the free venation of the true Polypodiums, yet shows 

 considerable resemblance to the species described by Hooker as J'. (Goniophlebium) 

 plectolepis. From this it is distinguished readily not only by venation, but also by 

 its adnate pinme and by having the sori borne much nearer to the margin than to the 

 costa, this last being an unusual feature. 



