PLEURIDIUM. 55 



gradually longer upwards, perichsetial bracts similar to the upper 

 leaves; nerve thin, vanishing below the apex, margin plane, 

 faintly serrulate at apex ; cells rather large, lax, pellucid, 

 rectangular-rhomboid below, narrowly linear or elongate-rhom- 

 boid above. Capsule on a very short seta, oval, shortly pointed, 

 pale brown, calyptra covering only the upper half of the capsule. 

 Antheridia naked among the perichsetial bracts. 



Vax.fi. strictum Braithw. (Phascum strictum Dicks.). Plants 

 very small, dull green ; leaves and bracts closer, narrower, 

 straight ; capsule nearly spherical. 



Hab. Fallow fields and sides of pools ; not uncommon. The var. j3, Scotland. 

 Fr. winter. 



This species is known from the others of the genus by its paler colour, the more 

 delicate and less rigid habit, by its leaves and perichEetial bracts being alike, and by 

 its larger cells. It is indeed more like Archidium atternifolium, although quite dis- 

 tinct in the fruit. The stem innovates below the capsule (which thus becomes lateral), 

 producing another fruit at its apex, and repeating the same process several times, so 

 that two or three capsules may be found on the same stem, one above the other. 



2. Pleuridium subulatum Rabenh. (Phascum subulatum 

 Huds.) (Tab. XII. F.). 



Stems short, simple, rarely branched or innovated, crowded, 

 dusky or yellowish green. Leaves small, lanceolate or ovate- 

 lanceolate, longer above ; perichaetial bracts erect or subsecund, 

 straight when dry, from a small oval base gradually subulate and 

 setaceous, very long ; nerve broad and ill-defined, continuous to 

 apex ; margin minutely denticulate, occasionally entire ; cells at 

 base rectangular or hexagonal-rectangular, above forming a very 

 narrow margin to the subula with narrower cells, sometimes 

 becoming extremely slender and elongated so as to be almost indis- 

 tinguishable from the nerve. Capsule yellowish brown or 

 reddish, oval or roundish oval, with a short obtuse point. 

 Antheridia naked in the axils of the perichsetial bracts. 



Hab. Sandy heaths and banks. Common. Fr. Apr. to June. 



The more rigid habit, and the long setaceous perichaetial bracts will readily dis- 

 tinguish this species from the last ; but it is much more difficult to define the 

 differences between it and P. atternifolium, except in regard to the position and form 

 of the male inflorescence, which in the latter is easily visible in the axils of the upper 

 leaves when a fruiting stem is placed under a low power of the microscope, but which 

 in the present plant is only seen after dissection. The subula of the perichsetial 

 bracts is in the present species more remotely and indistinctly denticulate, sometimes 

 quite entire ; while in that the denticulations, though minute, are more crowded and 

 numerous and consequently more conspicuous, and the cells are smaller. The apical 

 innovations also, which are common though by no means constant in that species, are 

 rarely present in our plant. 



