376 
DR JOHN M‘LEAN THOMPSON ON THE 
the annulus in extension. It is of an advanced vertical type, with a well-defined 
stomium. A more common condition is that shown in fig. 33. The back of the 
annulus is vertical, but the stomium passes obliquely down the cheek of the 
capsule, so that only the basal indurated cells re-enter the median plane. In some 
cases the annulus is broken, as in fig. 37. In others lignification is imperfect at 
the back or top of the annulus (figs. 36, 38), or the number of indurated cells may 
be increased, so that any condition ranging between a local doubling and a biseriate 
annulus may be found (figs. 36, 34). In the foregoing types the back of the annulus 
is vertical and is usually decurrent to the stalk, and a definite, though variably 
constructed, stomium is always present. 
But in some sporangia the condition shown in fig. 30 exists ; in others, the 
arrangement is as in fig. 39. In the former the stomium is well defined. The 
broken annulus passes obliquely over the capsule, and, instead of descending to 
the stalk, it terminates on the bulging cheek. In the latter there is no stomium, 
but the indurated cells form a crescent on the summit of the capsule. 
Spores. — The spores are tetrahedral (fig. 32), and resemble those of Plagiogyria 
semicordata, Kze. The highest spore-count made was 52, the lowest 46. 52 is 
probably the typical spore-number. 
The vertical uniseriate annulus is relatively uncommon in Llavea. The cap- 
sule form is fairly constant, and suggests no ready explanation of the prevailing 
irregularities of the annulus. As in Jamesonia, the sporangial-stalk is of the 
uniform advanced type. It may be reasonably suggested that in Llavea also 
upgrade tendencies in sporangial construction are shown, and that the slender 
three-rowed stalk, the occasional vertical annulus, and the moderate spore-output 
are features of advance. As in questions of affinity, so also with the study of 
Text-fig. 12. 
