﻿Evans: The genus Plagiochasma 289 



ing at the apex, margins undulate-crenate, more or less crispate, 

 mostly 1-3 cm. long and 5-10 mm. broad, thickness of thallus 

 about one sixth the width ; epidermis composed of thin-walled cells 

 with distinct trigones and a thin smooth cuticle, the cells about 

 30 n in diameter; pores slightly elevated, rather small, surrounded 

 by about six (four to seven) radiating series of cells with two or 

 three cells in each series, radial walls slightly thickened ; aeriferous 

 layer about three fourths the thickness of the thallus in the median 

 portion, fairly compact with the air spaces about as wide as the 

 green cells or even narrower close to the epidermis; ventral scales 

 lunulate or ovate, purple, slightly overlapping, irregularly sinuous- 

 dentate along the margin with contorted cells, bearing evanescent 

 slime-papillae, cells containing oil-bodies few and scattered, the 

 scales abruptly contracted into one or (more rarely) two large, 

 broadly ovate appendages, short-apiculate or abruptly acute at 

 the apex, irregularly sinuate-dentate along the margin or bearing 

 one or several sharp teeth or even one or two sharp basal lobes: 

 inflorescence monoicous (autoicous) : cf inflorescence borne on a 

 short ventral branch: $ receptacles borne singly or in tandem 

 pairs; peduncle mostly 1-1.5 cm. long; carpocephalum concave 

 at the apex, or obtusely indented, and two- or three-lobed with 

 apiculate lobes, maturing two or three sporophytes; scales of 

 carpocephalum lanceolate to narrowly ovate, irregularly sinuate 

 on the margin or with an occasional tooth : spores about 80 ju in 

 diameter, yellowish brown, minutely verruculose, regularly reticu- 

 late, spherical face usually with eighteen to twenty meshes (ten 

 to twelve marginal), plane faces with about seven (five to eight) 

 meshes, those near apex of pyramid less distinct ; elaters gradually 

 attenuate, mostly 270-325 /jl long and 12 fi wide in maximum 

 diameter, spirals usually three, often coalescing along a longi- 

 tudinal line. [Fig. 5.] 



The following specimens have been examined : 



Chiapas: San Cristobal, altitude 2,100 m., November, 1907, 

 G. Munch 5607 (distributed by Levier) . 



Sonora: Huchuerache, December, 1890, C. V. Hartman 307 

 (Lumholtz Expedition). 



Vera Cruz: Orizaba, F. Muller (type); February, 1885, W. G. 

 Farlow; January, 1892, /. G. Smith; December, 1900, Conzatti &■ 

 Gonzales; November, 1908, Barnes & Land 685; on wet ground, 

 Cordova, February, 1885, W. G. Farlow; on wall along roadside, 

 Cordova, February, 1907, Miss L. Maclntyre; along sides of Metlac 

 Gorge, October, 1908, Barnes & Land 640, 639. 



Gottsche likewise reports the species from Chinantla, Puebla, 

 F. Liebmann. No other localities are at present known. 



