302 Alexander W. Evans, 



and there are no trigones. In M. aurantiaca the wings bear scattered 

 hairs as in M. scyphigera, but the thallus is strongly convex, the 

 wings are only twelve cells wide, and there are no trigones. Stephani 

 makes no mention of gemmae in any of his descriptions. 



JUNGERMANNIACEAE 



IV. Plagiocliila Dumort. 



The genus Plagiochila is one of the largest genera of Hepaticae, 

 nearly eight hundred species being recognized by Stephani in his re- 

 cent monograph.^ With but few exceptions these species are trop- 

 ical, and many of them seem to be exceedingly local in their distrib- 

 ution. In spite of their considerable size the species are extremely 

 difficult to determine, the differential characters being often based 

 on the type of branching present, the shape of the leaves, the number 

 and peculiarities of their teeth, the size of the leaf-cells, and the nature 

 of the local thickenings in their walls. The bracts and perianths 

 also yield characters of importance, but the determination of speci- 

 mens must often be made without the assistance of these organs; 

 in fact they are known in comparatively few species. It will be seen 

 at once that most of the differential characters used are subject to 

 more or less variation, and this of course adds appreciably to the 

 difficulties of gaining a correct comprehension of the species. The 

 present collection contains nine Plagiochilae in sufficient quantity 

 to warrant determination; five of these are referred to described 

 species, and the others are proposed as new. It is to be hoped that 

 this course will not add to the confusion already prevalent in the genus. 



4. Plagiochila altemans Lindenb. & Gottsche 



Plagiochila altemans Lindenb. & Gottsche; G. L. & N. S}^. Hep. 

 648. 1847. 



On earth, San Miguel, 5,000-6,000 feet, July 24, 1911; on a damp 

 rock, Lucma, 7,000 feet, August 7, 1911. 



Plagiochila altemans was originally described from specimens collec- 

 ted by Liebmann in the province of Oaxaca, Mexico. It was after- 

 wards reported by Spruce from Bolivia, Rusby, and Costa Rica, 

 Hyde, and by Stephani from Venezuela, Funck. The Peruvian 

 specimens agree closely with the published descriptions and also 



Bull, de I'Herb. Boissier II. 2 — 6. 1902— 1906. 



