102 A MANUAL OF MOSSES 



broadly oval or turbinate, erect, sjmmetric, about 0.6-0.8 mm. 

 high, exannulate, more or less castaneous, when dry and 

 empty smooth and turbinate-hemispheric ; lid broadly convex 

 to flattish with a beak about one-half as long as the urn; 

 exothecial cells medium-walled, castaneous, pellucid, irregular- 

 ly quadrate to rectangular, the upper two or three rows at the 

 rim much smaller, rounded-quadrate, obscure; spores orange- 

 pellucid or brownish-pellucid, minutely punctulate, large, .026 

 -.030 mm., mature from autumn to spring. 



On moist soil in grasslands, along streams, etc., Europe, 

 Asia, northern Africa, and from Ontario to New England and 

 Pennsylvania, and in Nevada. Rare in our region. 



McKean : Corydon Street, Bradford. D. A. B. 



(Figured). 



11. DESMATODON Bridel. 



Autoicous : slender plants in mostly low, soft, green to 

 yellow-green ttifts, dense to loose : stem mostly with central 

 strand, thickly foliate, forking; leaves when dry appressed and 

 more or less plicate, when moist erect-spreading, carinate to 

 concave, obpvate to ovate or lance-linear, mostly with recurved 

 margins below, plane above, above often serrate, sometimes 

 margined ; costa mucronately or aristately excurrent, both 

 costa and lamina papillose; leaf-cells loose, thin-walled, above 

 rounded-quadrate or more or less hexagonal or rhomboidal, 

 below rectangular and long-hexagonal, hyaline, smooth : seta 

 elongate, mostly straight; capsule erect, inclined, or even 

 pendent, mostly symmetric, ovate to cylindric ; annulus persis- 

 tent or falling away in pieces ; peristome inserted below the 

 rim of urn, the basal membrane forming a tube which is slight- 

 l)^ exserted from the urn, thickly articulate, teeth rather broad, 

 divided to the base into two or three flat, filiform, papillose, 

 divisions, united here and there, usually twisted; lid stoutly 

 and obliquely rostrate, with the cells more or less spirally ar- 

 ranged ; calyptra cucullate, smooth, long-rostrate ; spores large. 



A small genus of 7 species, mainly on rich humus-soil in 

 the mountains; one species in our region. 



1. Desmatodon arenaceus Sullivant. 



(D. ohioensis Schimper; Didymodon arenaceus Kindberg). 



(Plate XIII) 



Gregarious to loosely cespitose, bright yellowish-green : 



stems short, in our specimens about 3 mm. long, radiculose at 



base; leaves erect-spreading when moist, crisped when dry, 



very small below but increasing to form a comal tuft above, 



from ovate to lance-ovate, the comal 2—Z mm. long, bluntly 



acute, short-apiculate, the margin minutely crenulate and more 



