145 
the Genus Streptopogon. 
occurs in Mitten’s herbarium the leaves are much damaged, 
especially at the apex and margins, by parasitic algae, &c., 
or are very old and decayed, so that only traces of the limb 
are here and there to be seen, while the marginal teeth have 
apparently been destroyed by erosion. The perigonial bracts 
are quite elimbate. 
The structure of the stem and of the leaf-nerve of clavipes 
is the same as that found in ery thro don tus. The stomata 
at the base of the capsule are rather numerous ; the long axis 
of the guard-cells is sometimes parallel to that of the capsule, 
at others at right angles to it. 
On the whole, 5. clavipes must be considered to differ 
specifically from .S. erythrodontus in its immersed or emergent 
capsule, wdth collenchymatous exothecial cells, in the less 
twisted peristome, in the cells of the operculum not being 
spirally arranged, the setulose base of the calyptra with longer 
hairs, the (usually) narrower and more regularly hexagonal 
cells in the upper part of the leaf, and in the inflorescence. 
The difference shown in the cellular structure of the oper- 
culum by two such closely allied species as S. erythrodontus 
and .S. clavipes is interesting as affording evidence that no 
generic importance can be attached to the spiral or straight 
arrangement of the cells of the operculum (cf. Muller (24), 
pp. 30, 406). 
L 
