514 Howe: PHYCOLOGICAL STUDIES 
Explanation of plates 25-30 
PLATE 25 
1-10. Halimeda Tuna 
. Portion of a segment (decalcified), in radio-vertical Sg showing peripheral 
igiciens utricles of the subcortical layer, and medullary fila 
2 and 3. Peripheral utricles and utricles of the ibaa lajes decalcified and 
teased out; the peripheral utricles separating rather easily. 
4. Peripheral utricles, decalcified, in surface view ; no fusion is noticeable. 
5. Vertical section by microtome through the filament of the central strand (decal- 
cified) at a node; just above the points of fusion the filaments are somewhat enlarged 
and are inclined to cohere 
6 o filaments from the central strand of a node, teased out, each formed by the 
fusion of two; just above the points of fusion there has been considerable coherence of 
the adjacent filaments and the outer layers of the filament-walls are more or less scarred 
and lacerated by the process of teasing the filaments apart. 
young simple sporangiophore. 
8. A sporangiophore ieng the margin of a segment, formed by the fusion of three 
filaments of the central stra 
. A forked hier a = from the margin of a segment, formed by the fasion of 
two ashibasts of the central strand. 
10. The beginning of a sporangiophore at margin of segment. (For sporangio- 
phores of a different ape see Plate 28, Figures 1 and 2. ) 
Figures I-10 are all drawn from formalin- -preserved material of our mo. 4207 
(Culebra Island, Porto eng ; 1-6 are magnified 40 diameters; 7-10, 24 diameters. 
11-20. Halimeda discoidea 
. Portion of a segment (decalcified), in radio-vertical section, showing peripheral 
waeiee of the subcortical layer, and medullary filaments. 
12 and 13. Peripheral utricles and distal ends of the utricles of the subcortical 
layer, decalcified, showing contact of the peripheral utricles and their occasional inter- 
locking. 
14 and 1§. Peripheral utricles, etc., showing fusion as well as interlocking. 
16. Utricle of the subcortical layer bearing numerous peripheral utricles 
17. Peripheral utricles, decalcified, in surface view, showing fusions ; fasions of 
two utricles are common ; near the upper left-hand corner and a little below the middle, 
in the figure, are fusions ‘of three utricles ; near the lower left-hand corner is a fusion of 
1B. Peripheral utricles, decalcified, in surface view, the dotted lines indicating the 
form and position of the distal ends of the utricles of the subcortical layer, which af — 
often Say) visible fen the peripheral utricles. : 
Filaments from central strand : nodes, showing incomplete fusion. 
20. Filament from central strand of node, showing complete fusion of two file: 
ments to form one, which afterwards hs into three. The filaments show? * 
Figures 19 and 20 are from the same node. 
Figures 11-20 are all drawn from eset ee material of our #0. 29% © 
(Caesar’s Creek, Florida) ; 11, 16-20 g o diameters ; 12-15, 55 diameter 
