132 American Midland Naturalist Monograph No. 6 



mamillate to conic-apiculate : dioicous: mature in May to June or July. 



A cosmopolitan common on earth in pastures, etc., also on dry banks, 

 stones, walls, etc. 



Known from the following counties: Allegheny, Butler, Centre, Clinton, Erie, Hun- 

 tingdon, McKean, Mercer, Washington, and Westmoreland. Specimen figured: Chestnut 

 Ridge above Hillside, Westmoreland Co., May 23, 1909. O.E.J. 



7. Bryum pseudotriquetrum [Hedwig, p. p.] Schwaegrichen* 



(B. ventncosum Dickson) 



This species is practically similar to Bryum bimum in everything except 

 that it is dioicous. According to Dixon and Jameson's Handbook the paler, 

 more lax-leaved, and more flaccid plants usually belong to B. bimum while 

 the more rigid and compact specimens are B. pseudotriquetrum, — but this is 

 not always the case. 



This species has much the same habitat and the same range as does B. 

 bimum, but in our region seems to be rare. In Porter's Catalogue it is reported 

 from Cresson, Cambria County, by James, and in the Carnegie Museum are 

 two specimens from two localities in McKean County which were distributed 

 as this species, but which prove to be synoicous and typically B. bimum. 



8. Bryum bimum [Schreber] Bridel 



{Mnium bimum Bridel) 



Plate XXIII 



Rather loosely but deeply cespitose and matted together with a chestnut- 

 colored tomentum: stems usually 3-6 cm high, rather sparsely branching; leaves 

 more or less long decurrent, 2-3 mm long, elliptic to oblong-lanceolate, acu- 

 minate, the margins revolute almost to apex, entire or serrulate above; costa 

 reddish, strong, percurrent to excurrent; leaf-cells rhomboid-hexagonal, the 

 basal reddish and inflated-rectangular, the marginal in three or four rows 

 linear-prosenchymatous and more or less yellowish-pellucid, forming a distinct 

 border; leaves when dry more or less shrunken, twisted, and appressed: seta 

 2.5-5.5 cm long, slender, flexuous, lustrous, castaneous; capsule 3-5 mm long, 

 pendulous, brown, subcylindric, tapering to a neck which is but slightly shorter 

 than the rest of capsule, slightly constricted below the mouth when dry and 

 empty, sometimes unsymmetrically up-curved; operculum broad, convex-mam- 

 illate; annulus large, revoluble; mouth deep chestnut, pellucid; peristome teeth 

 linear-triangular, yellowish-pellucid below, sub-hyaline and papillose above, 

 strongly trabeculate, lamellate, divisural zig-zag; basal membrane of inner 

 peristome half the height of teeth, the segments a little shorter, hyaline, carin- 

 ately split, cilia 3, strongly appendiculate; spores yellowish, .014-.016 mm, 

 minutely "punctulate" or granular: synoicous: mature in July. 



On wet soil, rocks, or decaying wood, in swamps or other wet places. 

 Cosmopolitan; in our region more common in the mountains and in the swampy 

 glaciated regions towards the northwestern corner of Pennsylvania. 



* Andrews in Grout (Moss Flora), regards B. bimum and B. pseudotriquetrum as 

 belonging to one variable species. According to the International Rules B. pseudotrique- 

 tium has precedence, as to name. 



