52 A MANUAL OF MOSSES 



Cambria: Cresson. James and Porter. (Porter's Catalogue). 

 2. Trematodon longicollis Richard. 



Cespitose, light green to brownish-green: stems erect, 

 usually about 5 mm. high ; leaves abruptly linear-subulate from 

 a concave ovate base, the subulation canaliculate, minutely ser- 

 rulate at apex; costa percurrent ; leaf-cells as in T. ambiguus; 

 perichastial leaves quite gradually long-acuminate: -eta 

 similar to T. ambiguus; collum twice as long as the urn ; urn 

 more strictly oblong-cylinclric ; peristome-teeth 16, narrow- 

 subulate, nodosely articulate, usually perforate rather than 

 cleft. Otherwise very similar to T. ambiguus. 



In old fields, etc., on sandy or clayey soil, in Europe. Asia, 

 and, in Xorth America, from New Jersey, Pennsylvania, and 

 Ohio southwards. Xot yet reported in our region, but to be 

 expected. 



3. PLEURIDIUM Bridel. 



Autoicous or paroicous, rarely synoicous : weak, green or 

 yellowish-green, cespitose or gregarious : stem with a central 

 strand, radiculose at base, perennial by means of fertile shoots 

 below the apex and by means of sterile Magella ; leaves mostly 

 terminal, erect-spreading, sometimes secund. linear-subulate 

 from a broader base, upwards weakly denticulate, sometimes 

 thickly imbricated; costa varying from weak and ending be- 

 low the apex to very broad and filling the whole acumen, often 

 rough-serrate dorsally ; seta mostly very short and erect, rarely 

 curved ; capsule mostly immersed and oval to ovate-globose, 

 short pointed, sometimes obliquely so, cleistocarpous, without 

 a collum; calyptra cucullate. cleft almost to the apex on one 

 side, covering scarcely half the capsule. 



About 30 species widely distributed, mainly in temperate 

 regions, on soil. Seven species occur in Xorth America, at 

 least two in our region. 



Key to Our Species 



a. Perichcetial leaves long and gradually subulate from a small oval 

 base: antheridia naked in the axils of the perichsetial leaves. 



1. P. subulatum. 



a. Perichsetial leaves abruptly long linear-subulate from an oval base: 

 antheridia gemmiform in the axils of the upper leaves. 



2. P. altcniifolinin. 



1. Pleuridium subulatum [Hudson] Rabenhorst 

 (Phasciuii sitbulatuni Hudson). 



Densely gregarious to cespitose, yellowish-green : stems 

 usually simple, about 2-5 mm. high ; stem-leaves lance-ovate, 

 the lo\ver shorter and more nearly ovate; comal and perichsetial 

 leaves much longer, more or less erect or subsecund, from a 



