348 A MANUAL OF MOSSES 



Key to the Species. 



a. Aquatic: alar leaf-cells forming a slightly differentiated group: seta 

 smooth. 



1. O. riparioides. 



a. Terrestrial: alar leaf-cells not diflferentiated: seta roughly papillose. 



2. O. hians. 



1. Ox3n:hynchium riparioides [Hedwig] New Combination. 

 (Hypnum rusciforme Necker; Eurhynchium rusciforme Milde; 



Hypmun riparioides Hedwig; Rhynchostegium rusciforme 



Bryologia Europsea). 



(Plate mi) 



Robust, in large tufts, dark to blackish below : stems 

 prostrate, woody, and usually denuded below; branches sub- 

 erect or ascending, usually more or less rigid and harsh, es- 

 pecially when dry; leaves ovate, loosely ascending or erect- 

 spreading, scarcely decurrent, about 2-2.5x1-1-5 mm., obtuse 

 to acute, plane-margined, somewhat concave, denticulate nearly 

 to the base ; costa thick below, reaching to one-half or two- 

 thirds the length of the leaf, or occasionally even sub-percur- 

 rent, often ending in a dorsal spine; median leaf-cells incras- 

 sate, linear-fusiform, about 10-12 :1, the apical and basal shorter 

 and broader, but no alar group diflferentiated, the median and 

 upper slightly dorsally spinose: seta smooth, about 1.3 cm. 

 long, castaneous, slightly twisted when dry; capsule castane- 

 ous, ovoid-oblong, somewhat constricted below the mouth 

 when dry, about 2-3 :1, dorsally turgid but scarcely curved, 

 inclined or nearly horizontal, the urn about 1.5-2 mm. long- 

 lid obliquely slenderly rostrate from a conic base, about two- 

 thirds as long as the urn ; annulus revolubl'e, usually 2-seriate ; 

 exothecial cells yellowish-incrassate, at the rim smalt and 

 rounded-quadrate, below rather large and irregularly oblong- 

 rectangular ; peristome-teeth slender, apically hyaline-papillose, 

 strongly trabeculate, dorsally plainly lamellate and finely cross- 

 striolate, margined, confluent at base; segments about as long, 

 usually carinately widely gaping but remaining unsplit at apex, 

 the basal membrane about one-half as high ; cilia 2-3, subulate, 

 nodose to sub-appendiculate, somewhat shorter Ihan the seg- 

 ments; spores weakly papillose, medium-walled, yellowish, 

 about .010-.013 mm., mature in early fall. 



On rocks in streams and rivulets ; Europe, Asia, northern 

 Africa, and from Newfoundland to Ontario and southwards in 

 the mountains to Georgia. Quite common in our region. 

 Cambria : Cresson. T. P. James. (Porter's Cata- 



logue) ., 

 Center : In rapidly flowing mountain-stream, 



Tussey's Mt., above Shingletown, July 

 15, 1909. O. E. J. 



