368 Mr. R. Spruce on the Musci and Hepatic<B of the Pyrenees. 



malous Polytrichum, which may possibly be a starved form of P. na- 

 num. It has the capsule subcernuous, nearly spherical ; the colu- 

 mella 4-sulcate, or rudimentarily alate (not terete as in typical P. na- 

 num) ; and the calyptra sheathing the whole of the capsule. 



183. P. abides, Hedw. Muse. Frond. 1. t. 14; M. P. 304; 

 Br. Europ. Pogonatum, p. 6. t. 8. 



Hah. Zo_3 in humidiusculis, prsesertim in arena rivulorum, al- 

 tius versus alpes ascendeus quani P. nanum. 



184. P. urnigerum, L. Sp. PI. p. 1573; M. P. 305; Br. Europ. 

 Pogonatum, p. 7. t. 9. 



Hab. Z0--2 in arenosis humidiusculis. 



185. P. oJpinum, L. Sp. PI. p. 1573; Br. Europ. Pogonatum, 

 p. 9. t. 10. 



Hab. Z2_4 P. c. in monte Crabioules. 



Var. caule valdc elongato, subsimplici; M. P. 306. — Hab. in 

 saxosis umbrosis vallis Lutour prope Cauterets. 



The curious way in which the epiphragm (the tympaniform dila- 

 tation of the summit of the columella) is attached to the peristome 

 in this and other Polytricha does not seem to have been anywhere 

 described. In P. alphmm it is originally placed at the base of the 

 teeth, to which it is attached by means of processes equaling them 

 in number and exactly covering their internal face. After the fall of 

 the lid, these processes are gradually detached and the epiphragm 

 rises, probably from the pressure of the full-grown spores beneath it, 

 so as to allow the latter to escape through the interstices of the pe- 

 ristome. When the epij)hragm is quite liberated, either naturally or 

 by art, the processes curve inwards upon its upper stirface (see PI. I. 

 fig. 1) so as to be with difficulty seen, unless the light be properly 

 regulated or the epiphragm be set up on its edge. The processes 

 are composed of only a single layer of cellules, which are so disposed 

 that their interstices form vertical lines corresponding to those on 

 the teeth. 



The adhesion of the epiphragm to the teeth is so great as to resist 

 the action of the columella to draw it down into the capsule, and 

 often ultimately to cause the rupture of the columella. The ragged 

 portion at the underside of the section (fig. 2) is where the rupture 

 takes place between the columella and the epiphragm. 



In P. urnigerum, aloides and nanum the epiphragm is attached to 

 the teeth in the same manner, but the processes are very thin and 

 tender, and when the epiphragm is detached by force they often re- 

 main adhering to the teeth. In P. angustatum (as also probably in 

 P. undulatum) the processes are united to each other by an inter- 

 vening membrane, which is granulated on the surface, while the pro- 

 cesses themselves are smooth and marked by lines similar to those 

 on the teeth : in other words, the epiphrtigm is bordered by an in- 

 flexed continuous membrane, by means of which it adheres to the 

 peristome, The figure of P. angustatum in ' Bryol. Europaea ' repre- 

 sents this pretty well, but no mention is made of it in the text. 



