POTTIACEAE. 123 
European Tortella tortuosa (L.) Limpr. may be considered the type. They 
are mostly rather robust, often of a yellowish colour, with the leaves usually 
strongly cirrate or spirally twisted when dry, margins erect or incurved, 
never recurved, a usually stout nerve, the upper cells opaque and papillose, 
the lower elongate, rectangular or linear, most frequently hyaline, so that 
the leaf-base is often conspicuously white. A frequent feature is _ the 
hyaline cells are continued higher in the leaf at the margin than r the 
nerve, so that the line of transition into the upper, chiseapiiiees “éella 
runs obliquely upwards and outwards. 
ortella stands, in fact, to Trichostomum in the same relation as Barbula 
to Didymodon. In the two more highly developed genera the peristome- 
teeth are long and spirally twisted to the left (viewed from within the spire), 
while the cells of the lid show a strong twisting in the same direction ; in 
Trichostomum and Didymodon the shorter, often imperfect teeth are upright, 
or with only a faint tendency to twist to the right ; and the rows of cells 
in the lid follow the dnmétion of the teeth. 
Key To THE SPECTEs. 
( Robust ; perichaetial leaves very lon phere Fic -.° 8. calycina. 
z ery long, g.- ye 
1 More slender ; ; perichaetial leaves inconspic ce Ae s 2 
very narrow, narrowly acuminate ‘S + -. 1. Knightii. 
a Leaves lingulate, obtuse and cucullate : : .. 2. rubripes. 
is pcg Knightii (Mitt.) Broth. in Engler and Prantl, Pflanzenfam., 
Musci, i, 397. 
Sea: Tortula Knightii Mitt. in Journ. Linn. Soc., iv (1859), p. 71; 
Handb. N.Z. FL. p. 420. Tortula caespitosa var. H. f. & W., 
Fl. N.Z., ii, 70. Barbula Knightii Jaeg., Adumbr., i, 281. 
B. nano-tortuosa C. M. in Hedw., vol. 37, p. 131. Trichostomum 
Tr. contortifolium R. = ter., i cit., p. 487. ir. avonense 
R: Br. ter., “op. ¢i., 481. ? Barbula Pisisdei C. M. in 
Hedw., vol. ‘37, p- 131 08). 
can hardly be any confusion with the other species. From the next it differs 
entirely in leaf-apex, and in the paler seta (though it becomes darker in 
full maturity, and, on the other hand, that of 7. rubripes is pale above 
until quite ripe). 
t may seem strange to refer the three species of Trichost omum of 
R. Brown to this plant, in view of the peristome, but there is no doubt that 
he described them from imperfect specimens; as a matter of fact there 
is not an operculate capsule in any of the specimens of these in his 
herbarium, all of them having old capsules eiaotle similar to overmature 
capsules of 7. Knightii, with which the leaves entirely a Tr. 
i apsule. 
rotherus states that nano-tortuosa C, M. is scarcely separable 
from T. Knightii, os out that the inflorescence is not dioicous, as the 
author states, but a ous. In view of the variability of T. Enightii I 
feel no hesitation in sie eesee it tothis species. B. Fristedtii C. M. is probably 
3* 
