ii8 Alexander W. Evans, 



be cited from the literature : without definite locality, Chile, Gay 

 (13, p. 505, and 18, p. 299, as Metzgeria criocaula var. chilcnsis) ; 

 Port Famine, Straits of Magellan, Andcrsson (i, p. 13, as Jun- 

 germannia prehensilis) ; Mt. Sarmiento, Tierra del Fuego, and 

 Basket Island, Spcgazzini 16, p. 255) ; Desolation Island, Welling- 

 ton Island, Mere-le Dieu Island, and Isthmus Bay, Savatier 

 (2, p. 245, as R. eriocaula var. chilensis) ; Tuesday Bay and Punta 

 Arenas, Naumann (19, p. 41, as Pscudoneura prehensilis) ; Rio 

 Aysen, Guaitecas Islands, and Puerto Blest, Lake Nahuelhuapi, 

 Argentina, Dusen (28, p. 19, as Aneura prehensilis) ; Desolation 

 Island, Dusen (9, p. 9, as A. prehensilis) ; Huafo, Atalaya and Hale 

 Islands, Peel Inlet, Skyring, and Canal Jeronino, Skottsherg (32, 

 p. 7, as ^. prehensilis) ; Almirantazgo and Lake Fagnano, Tierra 

 del Fuego, Skottsherg (32, p. 8, as A. prehensilis). It is probable 

 that some of these records are based on the following species. 



The plants of R. prehensilis are large and conspicuous and either 

 creep over other bryophytes or grow in loose tufts. Their color is 

 yellowish or brownish green, turning darker with age. Although 

 the thallus lacks the remarkable lamellate outgrowths found in 

 R. fuegiensis, it is almost as highly differentiated. The rigid main 

 axis is prostrate or somewhat ascending at the apex and continues 

 its growth indefinitely, the living portion being mostly 2-5 cm. in 

 length. Its width is usually 0.5-0.9 mm, and its thickness 0.35-0.6. 

 Although this indicates a certain amount of flattening, as the 

 descriptions state, the edges of the axis are rounded in cross section 

 and are never, so far as the writer's observations go, extended as 

 wings, except sometimes in close proximity to the branches. The 

 apical portion is crowded with slime-papillae, which excrete an 

 unusually large volume of transparent mucus-like matter, some- 

 times faintly tinged with yellow. 



The histological structure of the axis (Fig. i, B) shows certain 

 features in common with R. fuegiensis and other species of the 

 genus in which the axis is robust and clearly differentiated. In 

 well-developed plants it sometimes attains a thickness of thirty 

 cells, the cells averaging about 20 /x in diameter. With the excep- 

 tion of two or three layers on the outside these cells are elongated 

 and form a slightly flattened strand. Their walls are more or less 

 thickened and supplied with pits. In the interior these walls are 

 pale or almost colorless and only slightly thickened, the pits being 



