374 ] TRANS. ST. LOUIS ACAD. SCIENCE. ij 
5. According to the presence or absence of peripheral bast- 
bundles : 
a. Without bast-bundles : Z lacusttis , Z pygmcea , Z Tuckermani, 
Z echinospora , Z saccharata, I. Bolanderi , Z riparia, ahd Z ^/#- 
nospora. 
b. With bast-bundles : Z Engelmanni, Z Howelli, I. flaccida^ I, 
meldnopoda , Z Butleri, Z Nuttallii, and I. Cubana. 
The comparative size or the sculpture of the spores, and the 
number and length of the leaves, furnish no legitimate grounds 
for classification; still it may be mentioned here, that the largest 
macrospores (0.45 to 0.80 .mill* in diam.) are found in Llacustris, 
Z Butleri) and Z riparia ; the smallest (0.25 to 0.45 mill.) in Z 
melanopoda, I.Jlaccida, and Z Engelmanni var. valida. 
The largest number of leaves, 50 to 200, are observed in the 
last mentioned form, in Z melanopoda and in Z Nuttallii; the small- 
and E Bolanderi. ’ ’ ^ ^ ' 
^ The longest leaves (15 to 25 inches long) we meet with in Z 
long) in Z pygmcea , Z melanospora , and Z . 
The 1 
best I c 
