Howe: Oropogon loxensis 



155 



Diagnosis : Thallus caespitose or prostrate, brown, subrigid, 

 branches nitidous, dichotomous. Spore i, muriform. 



Description : typical : Thallus caespitose or prostrate, filamen- 

 tous, slender, subrigid, brown to light brown, commonly black- 

 ening; branches terete to subterete; cortex glabrous or nitidous, 

 occasionally rimulose ; primary branches dichotomous, flexuous, 

 entangled (max. length 15 cm.); secondary branches dichoto- 

 mous, flexuous; fibrils short, furcate. Apothecia lateral, com- 

 mon, small (max. diameter 2 mm.), concave, convex, or ap- 

 planate, innate-marginate, disk concolorous, chestnut or dark 

 brown. Spores 55-134 X 28-48 /x. 



Substrata: The plant is reported to grow both on the ground 

 and on trees; but the collector's labels that I have examined 

 are without data in regard to the substratum (see Hue, Lich. 

 Ext. Europ. 95. 1901). 



Geographical distribution : Confined within our area to the 

 alpine regions of Mexico. It has been collected on Mt. Ori- 

 zaba, and at Neveria and Alvarez. Outside of Mexico it has 

 been collected in Japan, China and Java, in Peru and Colombia, 

 South America, and on the island of Jamaica (Merrill, Bryl. 

 14:37. 1911). 



Observations: A subspecies was proposed by Nylander, i. e., 

 Al. Loxensis var. atroalbicans (Lich. Novo Gran. Prod., Act. 

 Soc. Sci. Fenn. 7: 20. 1863). It is simply a color form de- 

 scribed as follows : " thallo proparte nigricante et pro maxime 

 parte albicante." The type No. 2746, collected by Lindig at 

 Choachi, Colombia, is now in the herbarium of the Museum 

 d'histoire naturelle, Paris. 



Specimens examined 



Sprague Herbarium, Boston Society of Natural History. 



Mexico: Mt. Orizaba, Fr. Muller. 



U. S. National Herbarium, Washington. 



Mexico: Alvarez, San Luis Potosi, 8,999 f^., Sept. 1902, Ed. 

 Palmer. 



British Museum of Natural History, London. 

 Colombia: Bogota. 



