426 TRANSACTIONS OF THE [Sess. lxxix. 



attached with broad hyaline, characteristic walls, "05-07 

 by •02- , 032 mm., thickly granular but soon showing a 

 tendency to become hyaline and then in double layer, such 

 cells outwardly, rather abruptly narrower and hyaline, 

 upwards cells soon bluntly quadrate but still showing the 

 broad hyaline walls, •02- - 027 mm. in longer diameter, near 

 margin and upwards to apex cells somewhat smaller and 

 showing within minute particles well defined, which present 

 much the appearance of stere'icls. 



Now, if the three larger species of this group are placed 

 closely alongside one another in a wet state, they present 

 mutual appearances of such a character that the eye alone 

 is sufficient to discern a close general affinity. A closer 

 inspection through a field lens confirms this view. Under 

 a moderate power of the microscope the configuration of 

 the leaves, the peculiar arrangement of the marginal 

 serratures, the rather unusual disposition of their upper 

 divisions, etc., point to a common origin; inspected more 

 closely under a higher power, the minuter structures and 

 configurations show manifest differences in each to such an 

 extent as fully to warrant specific distinction. 



As all this is merely preliminary to what I may have 

 to say in another communication, I shall desist meanwhile 

 from asserting conditions necessary to what may be called 

 a theory, such as is shaping itself, as time goes on, more 

 definitely in my mind. 



While searching for specimens of Leptodontium gem- 

 mascens (Mitt.) on the old thatched roofs of the highland 

 cottages, its usual habitat, I came across another moss 

 which had, to the best of my recollection, not been pre- 

 viously observed, viz. : — 



Ca/m/pylopus obtectus, sp. n. — In dense broadly expanded 

 convex tufts of a vivid green above, in thickness about 

 one-eighth to nearly a quarter of an inch, below this 

 abruptly changing to a pale yellowish colour ; stems 

 upright generally single, but occasionally emitting short 

 lateral branches ; leaves closely appressed to stem when 

 dry, slightly spreading but straight when wet, closely 

 arranged around stem, broad, short and bluntish at apex 

 (•05 mm. broad), which has two or three teeth but none 

 elsewhere throughout leaf ; nerve broad, nearly half that 



