140 American Midland Naturalist Monograph No. 6 



All Pennsylvania specimens in the Carnegie Museum Herbarium which 

 were labeled M. rostratum are non-collenchymatous and the leaf-cells are defi- 

 nitely arranged in series radiating from the costa. 



The specie'^ is reported from our region as follows: Cambria Co.: James. (Porter's 

 Catalogue). Lycoming Co.: McMinn. (Porter's Catalogue). 



7. Mnium cuspidatum Linnaeus, Hedwig 



(Mnium sylvaticum Lindberg) 

 Plate XXV 



Loosely cespitose in large light to dark patches: stems branching with 

 sterile shoots prostrate or sub-erect, in our specimens usually about L5-3 cm 

 high, reddish, radiculose below; leaves decurrent, oblong-oval, acute, the upper 

 tending to obovate, those on the branches more rounded or oval, all shortly 

 cuspidate and serrate in the upper half or two-thirds with a single row of short 

 one-celled teeth, occasionally some teeth two-celled, the border of 3-5 rows of 

 incrassate, linear, yellowish-pellucid cells; costa confluent with the border in 

 the apiculate apex or ending a little below the apex; leaf-cells about .020-.025 

 mm, incrassate, collenchymatous, hexagonal to somewhat rounded, the basal 

 tending to rectangular: seta solitary, pale yellowish or brownish, erect; capsule 

 pale yellowish or brownish, sub-pendulous, oblong-oval, rather abruptly nar- 

 rowing to the seta, the base and mouth brown; operculum conic-obtuse; teeth 

 yellow, lance-linear, papillose above, divisural indistinct; inner peristome a little 

 shorter, the basal membrane extending to the middle or a little above, the 

 basal part of the segments more or less irregularly fenestrate with rounded 

 holes, the upper part of the segments finally gaping or breaking apart; cilia 

 three, Unear, somewhat appendiculate, the inner peristome brownish-pellucid, 

 the tips of the segments and the cilia being paler and papillose; spores rounded, 

 faintly papillose, yellowish, about .025 mm in diameter: synoicous, mature 

 in May. 



In moist woods on earth, stones, rotten logs, etc. Common and widely 



distributed over the temperate parts of Europe, Asia, and of North America. 



Common and now known from seventeen counties in western Pennsylvania and prob- 

 ably occurs in all. Specimens figured: Ohio Pyle, Fayette Co., May 30, 1908. O.E.J. 



8. Mnium medium Bryologia Europaea 



(Astrophyllum medium Lindberg) 

 Plate XXV 

 Widely and rather loosely cespitose, large, light to dark green: stems 

 erect, up to 5 cm in our specimens, branching at the base, densely covered with 

 a brovm felted tomentum, sterile shoots long and prostrate or ascending; leaves 

 distant, shriveled when dry, ovate to oblong, somewhat narrowed and slightly 

 decurrent at base, rather obtuse at apex, cuspidate, narrowly margined all 

 around, sharply serrate from near the base with mainly one-celled teeth, the 

 comal leaves rosulate, and up to 5 x 15 mm; costa reddish, strong, percurrent 

 cuspidate; leaf-cells large, rounded above to elliptic-hexagonal towards base, 

 the margin consisting of about two rows of linear, much incrassate, more or 

 less colored cells, the laminal cells all incrassate and collenchymatous and in- 



