1897 ] 4 NEW QUILLWORT 35 
pean students of the Isoetacee that the largest plants of a given 
species contain relatively the fewest microsporangia, but I think 
that no such extreme instance as this of our present species has 
been recorded, and it is quite in contrast with the habit of 7. 
Engelmanni, its nearest congener, in which microspores can 
always be found, excepting when the plants are very small or 
poorly developed. 
The larger plants of /, Eatont produce annually thousands of 
macrospores, probably continuing to do so for many years, and 
yet the station where this species occurs is far from being fully 
occupied, so that this infrequent occurrence of the microspores 
would seemingly account for the dispersed manner in which the 
plants are found to grow. It is to be noted, on the other hand, 
that the sporangia are very large, often a half inch long, each 
microsporangium containing doubtless several million spores. 
The leaves of /. Engelmanni are found always in my experience 
to contain peripheral bast bundles. In this species they are 
present in some leaves, but not in others of the same plant, and 
from some plants they are apparently altogether absent. They 
are often weak, but occasionally well developed, and occupy the 
same position as in /. Engelmannt. 
Those who are familiar with the classification of the species 
of Isoetes, as elaborated by A. Braun and adopted by Engel- 
mann, Baker, and Motelay, will notice that the position of 7 
Eatoni is quite abnormal when considered in reference to its” 
mode of growth and to the presence of bast bundles. 
The sculpture of the spores in this species is labyrinthiform- 
convolute, having about the same appearance as brain coral, the 
walls being wide, and not, as in J. a composed ses 
fragile laminz. 
A marked feature of the macrospores is that the comuiachiel 
ridges are perfectly straight. The angle which these ridges 
make with the equatorial plane of the spore is sometimes so. low | 
that the upper end of the spore is very flat, but the average 
angle is about twenty-five degrees. This isi the ge nebay a 
ie — eae Loam is nes noticed in 
