POTTIA. 169 



The capsule in this species is of a peculiar form, as is best shown by the figure. 

 Sometimes, however, it more closely resembles that of the last species, but is larger 

 and longer. That species has smaller leaves with much smaller areolation, more 

 papillose and obscure ; indeed, the foliage of P. recta is rather Phascoid than Pottioid, 

 while the present species in the leaves closely resembles some of the other species of 

 Pottia. The fruit, however, will readily separate it. 



The var. Thomhillii, which I have not seen, was by Wilson considered as 

 possibly a distinct species, and the characters as detailed by him are certainly 

 striking. 



P. bryoides is a variable species, and other forms have been described as varieties, 

 but apparently on slender grounds ; one form (var. filifera) has the nerve excurrent 

 in a long hair-like point. 



3. Pottia Heimii Furnr. (Gymnostomum Heimii Hedw.) 



(Tab. XXV. I.). 



A comparatively tall species, with the stems \-\ inch high, 

 but very variable in this as in other respects, tufted, yellowish 

 green. Leaves increasing in size upwards, lower broadly 

 lanceolate, those at the top of the stem long, narrowly oblong- 

 lanceolate, acute and slightly acuminate, spreading when moist, 

 appressed and slightly twisted when dry ; margin plane, serrated 

 towards apex ; nerve reddish, usually slightly excurrent ; cells in 

 the lower half of the leaf elongated, rectangular, lax, hyaline ; in 

 upper part rather large, hexagonal-rhomboid, chlorophyllose, 

 rather incrassate, papillose. Seta long (J--J inch), rather thick, 

 twisted when dry ; capsule obovate-oblong, rather large, but 

 variable, thick-walled, narrowed at base, pale brown, wide- 

 mouthed when empty ; calyptra smooth ; lid obliquely rostrate 

 from a broad flat base ; columella attached to lid, at maturity 

 lengthened beyond the mouth of the capsule, elevating the lid and 

 retaining it for some time ; peristome none. Autoicous or rarely 

 synoicous. 



Hab. Muddy and sandy ground near the sea. Frequent. Fr. spring. 



This is one of our few distinctly maritime mosses ; it somewhat resembles robust 

 forms of P. intermedia, but it has a different facies from any of the other species, by 

 which it is easily recognised, the long, stout seta greatly contributing to this. It is 

 also quite distinct in the leaf apex, and although among its many variations it occa- 

 sionally has the leaves entire, it is rarely that it may not be known by this character. 



The lid, elevated above the mouth of the capsule and remaining attached to the 

 columella, is a very curious and striking characteristic of this species during the time 

 that the fruit is mature. 



The plane margin of the leaf would distinguish doubtful or barren forms from P. 

 intermedia; the leaves are also usually of a more solid texture than in the allied 

 species. 



4. Pottia truncatula Lindb. (Bryum truncatulum L. ; Pottia 



truncata Furnr., Schp. Syn.) (Tab. XXV. J.). 



In loose tufts or patches, dark green ; ^-inch high, slightly 

 branched. Leaves quinquefarious, spreading, soft, twisted when 



