650 MR JOHN M'LEAN THOMPSON ON 



and, between these, transitional forms exist (text-fig. 9, and figs. 55-62, 67-68). 

 The large sporangia contain small numbers of large spores, the small sporangia 

 larger numbers of small spores (figs. 64, 65, and 66). The small sporangia are 

 invariably short-stalked, but in form they are very variable. In some cases the 

 capsule is globular, in others it is ovoid or almost pear-shaped, while frequently 

 it is very lopsided (figs. 55-59, 61, and 62). The annulus is variable in position 

 and form. It is seldom, if ever, perfectly regular, and is frequently very irregular. 

 In a few cases it was found to be almost horizontal, passing round the capsule 

 as an irregular and broken ring, and having no organised stomium (figs. 61 and 62). 

 But in the majority of the sporangia examined the annulus was almost vertical, 

 though typically irregular or broken. These sporangia possessed a definite stomium 

 (figs. 55-58). Figs. 55-58 show a single sporangium from above (fig. 57), below 

 (fig. 58), back (fig. 55), and front (fig. 56). From these it is apparent that 

 the annulus begins at the stalk, passes obliquely and with irregularities upwards, 

 and, having passed over the top of the capsule, descends to the stalk once more 

 as an irregularly developed stomium. The annulus is, then, interrupted by the 

 stalk. A more regular — though also more oblique — annulus is represented in 

 back view in fig. 59, while in fig. 60 the wall of a sporangium which has been 

 opened out is represented. It is apparent that in this case the annulus began 

 close to the stalk, and passed almost vertically over the summit of the capsule. 

 But here an irregularity arose. This led to a displacement of the stomium, so that 

 it did not descend directly to meet the stalk, but, having passed to one side of it, 

 came into close contact with the end of the annulus which had met the stalk. 



The number and the size of the spores which were found in those smaller 

 sporangia varied. The largest number of spores found in any small sporangium 

 was 32, and such numbers as 30, 29, 28, and 26 were frequently counted. The 

 spores are tetrahedral, and the lines of junction of the tetrads are well marked 

 (figs. 64 and 65). The exospore is beautifully sculptured, there being numerous 

 small areas enclosed by wavy borders, and possessed of little mounds which give 

 an added roughness to the spore coat. The smallest type of spore found in a 

 small sporangium is shown in fig. 65. It was taken from a sporangium containing 

 32 similar spores. The largest type of spore found in a small sporangium is shown 

 in fig. 64. It was taken from a sporangium containing 29 similar spores. 



One of the largest sporangia found is represented in figs. 67 and 68. It is 

 apparent from the back view (fig. 68) that the annulus stops short at the stalk 

 and passes irregularly over the top of the capsule. The stomium is shown in fig. 

 67. It is separated from the annulus, and passes downwards obliquely to the 

 stalk. The largest number of spores found in a large sporangium was 16 ; 14 was 

 an average count, and 12 was a rare number. A typical large spore is shown in 

 fig. 66. It resembles the smaller spores in form and external markings, but differs 

 from them remarkably in size. Two large sporangia contained both large and 



