164 TORTULACE^:. 



Somewhat variable in size and in serrature of the bracts, this plant may always 

 be recognised by the rounded, not apiculate capsule, and the bracts connivent above and 

 concealing the fruit, not spreading and open as in Phascum ; the areolation, too, is 

 usually more elongated and rhomboid, and smooth. From A. triquetrum it differs in 

 the more elongate plants, more acute in outline, with the nerve of the leaves 

 straighter, less conspicuous, not recurved in the mucro. The upper cells in both 

 species are slightly incrassate, but not markedly so. 



* Acaulon mediterraneum Limpr. (Tab. XXV. B.). 



Differs from A. muticum in the rather more slender and 

 slightly curved outline of the plant, the leaves and bracts usually 

 less denticulate, the outer of the two bracts considerably shorter 

 than the convolute, inner one. Seta very minutely curved, or 

 straight. Capsule with a distinct obtuse apiculus. Male flower 

 adhering to basal radicles of the fertile plant. 



Hab. Bank at Douglas, I. of Man (Holt, 1886). 



Except in the characters above described, the specimens which Mr. Holt has 

 kindly sent me for examination show no difference from A. muticum, either in the 

 curvature of the seta or the smoothness of the spores. The seta I find as nearly as 

 possible straight, the spores minutely tuberculate as in A. muticum, the leaves and 

 bracts constantly more or less denticulate, and though less strongly so than is often 

 the case with the above, yet always more so than I have frequently found in that 

 species, which sometimes occurs with the leaves entire or only faintly sinuose, even in 

 the type. 



The unequal bracts and the more distinctly apiculate capsule are I believe the 

 sole points that can be relied upon, and although of some value, they do not, I think, 

 constitute sufficient difference to allow the plant specific rank. Almost all writers 

 describe A. muticum as exhibiting a short obtuse apiculus, and its greater distinctness 

 here can therefore only be looked upon as a question of degree. 



2. Acaulon triquetrum CM. (Phascum triquetrum Spruce ; 

 Sphasrangium triquetrum Schp., Syn.) (Tab. XXV. C). 



Resembling the last but smaller, often golden brown ; the 

 plants bulbiform, almost globose, rounded and obtuse in outline ; 

 the bracts rather more numerous, usually three, acutely carinate 

 as to give a triquetrous outline to the plant when viewed from 

 above ; the nerve strong, excurrent in a recurved apiculus, the 

 upper margin slightly recurved. Capsule on an arcuate seta. 



Hab. On the ground on the south coast ; very rare. Fr. early spring. 



Distinguishable from tht first species by the characters italicised above, although 

 somewhat approached by the var. minus of that plant. 



37. PHASCUM Schreb. 



Minute, cleistocarpous plants. Leaves entire, ovate or lanceo- 

 late, upper areolation usually papillose. Calyptra cucullate. 



