586 ALEXANDER W. EVANS 



In the Juan Fernandez specimens the thallus, which is about 3 cm. long, 

 is irregularly lobed, the lobes being rounded and measuring 5—7 mm. in width. 

 Sometimes the margin shows irregular sinuations or vague tooth-like outgrowths, 

 those best developed being three or four cells long and three to eight cells 

 wide at the base. Except for the outgrowths, which may be only one cell 

 thick, the thallus lacks a unistratose border. As in all known species of 

 Megaceros the thallus is solid and shows no intercellular spaces filled with slime. 

 It is bounded above and below by a layer of small cells, about 20 [j. in width, 

 and the much larger internal cells are in about eight layers in the thickest 

 portions. These internal cells are mostly 60 — lOOji in width and 50 — 70 [ji. in 

 height. The cells are everywhere thin walled and colorless, but some of the 

 internal walls show a delicately pitted condition, the pits being irregular but 

 showing a tendency to be narrowly fusiform and parallel; the walls thus acquire 

 a reticulate appearance. The chloroplasts, in number and in distribution, agree 

 with Goebel's descriptions. 



The involucre, which sometimes flares at the mouth, is mostly 4 — 6 mm. 

 long and i mm. wide. The capsule is 2 — 2.5 cm. long and about 0.5 mm. in 

 diameter. The spores are pale yellowish green and average about 25 [i. in 

 greatest width. The whole surface is very minutely punctulate, and the spher- 

 ical face bears in addition twelve to sixteen verrucae in the form of short 

 cylinders or truncate cones, about 2 \i. in diameter and 2 {/, or less in height. 

 The elaters are mostly one-, two-, or three-celled and are 60 — 200 ^ long by 

 8 a in diameter. The single spiral band is yellowish brown in color and about 

 8 ;j, in width. 



The spores of the Juan Fernandez specimens are almost exactly like those 

 of the West Indian M. vincentianus (Lehm. & Lindenb.) Campbell and agree 

 equally well with those of M. cristisporus Steph. of Costa Rica. Stephani, 

 in fact, describes several other tropical American species with similar spores. 

 M. vincentianus is distinguished by a minutely lacerate thalline margin, M. 

 cristisporus by a shorter involucre, and the other species (according to the de- 

 scriptions) by slight differences of one sort or another. In M.fuegiensis, which 

 Stephani records from Tierra del Fuego only, the spores are said to be 36 [i 

 in diameter, but the description agrees in most other respects with the Juan 

 Fernandez plants. 



Area of distribution: Tierra del Fuego; Juan Fernandez. 



The following numbers represent sterile Anthocerotaceae, which are not 

 in a condition to be determined: — 



Masatierra: waterfall in Pangal. 205 m. (no. 115, 116); V. Anson, near 

 Plazoleta, on stones (no. 117). 



Masafuera: Q. de las Casas, innermost accessible part, 200 m. (no. 118); 

 Q. de la Loberia, in water (no. 119). 



In all probability these specimens, if sporophytes were present, would be 

 referable to one of the preceding species. 



Printed ^V" ^930- 



