116 
the time of fruiting (fall). The leaves are abruptly pointed with a 
short and stout mucro. The sporangia are numerous, often double 
from a single cell (as in Plate xlil, Fig. 3). The coronula is peculiar 
in its oblique direction and sub-persistent character, and becomes de- 
tached when the sporangium is quite old. The dense interweaving 
of the divisions 'of the leaves surrounding the fertile heads suggests 
the specific name. 
Gathered from deep water (10-15 f^-) ^^ Cayuga Lake, N. Y., 
August, 1882. I have also received a fragment from Canada, col- 
lected by Miss Cary, and sent by A. L. Kemp, LL.D. 
Explanation of Plate xxxvn. — Fig. i. Plant, natural size from Arizona. 
Fig. 2. Sketch of the base of a verticil showing the simple, sterile leaves, not longer 
than the compact fruiting verticils, which are incompletely outlined. Fig. 3. A 
portion 0/ the stem, showing two crowded fertile whorls with numerous sporangia 
at the base of the leaves. Fig. 4. A mature sporangium. Fig. 5. A mature 
nucleus. Fig. 6. A tip of a leaf. (Figures 2 to 5 are from the Arizona plant, and 
Figures 7 and 8 from the dwarf Canada plants). Fig. 7. A node of a leaf, the 
anthoridium having fallen. Fig. 8. A sporangium prior to the falling of the 
coronula. 
Explanation of Plate xxxviil — Fig. i. Plant, natural size. Fig. 2. A fer- 
tile node magnified 25 diameters, showing the fertile cells all on the ventral aspect, 
usually with two sporangia and one antheridium. In some places the fruit has been 
rubbed off in preparing the specimen for the camera. Fig. 3. A fertile node of 
a leaf, ventral aspect, showiqg two antheridia and one sporangium. Fig. 4. Dorsal 
aspect of a fertile node, showing three unequal, 3-cellcd leaflets. In all these fig- 
ures space does not permit the delineation of the long terminals of the leaves. Fig. 
5. The apex of a sporangium, showing the evanescent coronula, magnified 2co 
diameters. Fig. 6. A mature nucleus with eight prominent, blunt angles, mag- 
nified 50 diameters. 
Explanation OF Plate xxxix. — Fig, i. Plant natural size. Fig. 2. A portion 
of a fertile verticil, with two nodes of a leaf and two fertile rays on the lower node, 
magnified^5 diameters. Fig. 3. A fertile leaf-node showing the stipes of two an- 
theridia, which have fallen, magnified fifty diameters. In this species we frequently 
find two antheridia (central) and two sporangia (lateral on the ventral aspect of a 
leaf; in which case there are usually but two rays on the dorsum of the leaf. Fig. 4* 
The coronula magnified 200 diameters. Fig. 5. A mature nucleus magnified 200 
diameters. Fig. 7. Tip of leaf. 
Explanation of Plate xl. — Fig. i. Plant, natural size (fresh specimens will 
modify this sketch). Fig. 2, A leaf magnified 25 diameters, showing the undi- 
vided sterile rays. Fig. 3. The tip of a sporangium, showing the persistent cor- 
onula X 200 diameters. Fig. 4. A mature nucleus, magnified 50 diameters. Fig. 5- 
The node of a sterile leaf, showing its division into 4 leaflets x 25 diameters. Fig. 
6. The tip of a leaflet magnified 50 diameters. 
Explanation of Plate xll— Plant, natural size, with the fertile heads on one 
branch at A, the other heads having been removed (as at B) to show the arrange- 
ment of the sterile leaves. Near the bottom of the stem there is a small verticil 
of sterile leaves. Fig. 2. A fertile shoot, taken at A in Fig. I, magnified 
5 times to show the general form. All the sterile leaves have been removed, ex- 
cept from the lowest fertile veriicil. Usually there are four sterile leaves, each di- 
vided into four leaflets, and two shoots bearing new fertile verticils from each ver- 
ticd. Some of the normally sterile leaves of the upper verticils become fertile. 
There are usually 5-6 successive series of fertile verticils, the uppermost bearing 
fruit in the verticil, and about six fertile leaves (magnified 5 diameters). Fig. 3- A 
fertile verticil with numerous, long-stipitate fruits, showing at B. the basal node of 
a leaf that has been removed; magnified 40 diameters. Fig. 4. The dorsal 
aspect of a fertile ray x 40. Fig 5. The ventral aspect of a node of a fertile ray 
(the antheridium removed), magnified 25 diameters. Fig. 6. The apex of a ray. 
showing the long slender point, ma Miified 2'>o diameters. Fig. 7. The coronula 
of a sporangium magnified 200 diamccrs. Fig 8. A maiure nucleus magnified 50 
diameters. 
