MOSSES WITH A HAND-LENS 67 



soil and occasionally growing in more moist situations. It is 

 exceedingly variable in its peristome and its size. Our plants are 

 mainly of the smaller size figured in the plate, but the capsules 

 are nearly always erect. It may usually be distinguished from 

 Astomum when sterile by its larger size and longer leaves. The 

 margins of the leaves are so strongly inrolled above as to make 

 them appear almost tubular. The capsules do not apparently 

 become wrinkled as shown in the plate until they have reached a 

 considerable age. The spores mature in spring. In Californian 

 forms the peristome is almost entirely lacking. 



BARBULA. 



The leaves of this genus are lanceolate from a broader base 

 (except B. unguiculata) and are somewhat contorted when dry 

 but scarcely crispate, margins revolute. The costa is percurrent 

 or barely excurrent. The capsules are nearly cylindric and the 

 peristomes strongly twisted. Tortella and Tortula are likely to 

 be confused with Barbula, but in Tortella the leaves are strongly 

 crisped when dry and the transparent cells at the base run up 

 the margin so that the boundary line between the transparent 

 and opaque areas is in the shape of the letter V. In all our 

 species of Tortula here described the costa is long excurrent into 

 a hair point. 



B. UNGUICULATA (Huds.) Hedw., the Common Barbula, is 

 our most common and most variable Barbula. The plants are 

 green to dirty green, ^4-inch high ; leaves erect-spreading or 

 slightly recurved when moist, spirally twisted when dry, lingulate 

 to oblong-lanceolate, obtuse. The costa is excurrent into a short 

 round mucro; margin recurved below, but plane above. The 

 perichaetial leaves are longer and more acute. The seta is red- 

 brown; the capsule oblong or cylindric, usually symmetric, with 

 beaked lid. The peristome teeth are long and slender, spirally 

 twisted in two turns. The spores mature from late autumn to 

 early spring. On damp earth, walls, and stones. Exceedingly 

 variable, especially in leaf forms, which may become lance- 

 linear, and even acute in the case of the perichaetial leaves. It 

 might be confused with Tortella caespitosa, but the leaves are 

 shorter than in that species; the margins are recurved and the 

 hyaline basal cells do not run up the margin. In general the 

 plants are much darker colored. 



