Howe: STRUCTURAL DIMORPHISM IN GALAXAURA 623 
One of the largest single collections at hand was that made by the 
writer on Condé Beach, Guantanamo Bay, Cuba, in March, 1909 
(no. 6460), where nineteen plants or fragments of plants were 
picked up on the shore (the species is apparently an inhabitant 
of rather deep water and is found washed ashore or by dredging 
in 7-18 meters). Of these nineteen, three were antheridial and 
of the ‘‘Spissae” structure,” three were cystocarpic and of the 
“Spissae” structure, twelve were tetrasporic and of the ‘‘Cam- 
eratae’’ structure, and the remaining one was apparently sterile 
and of the ‘‘Cameratae” structure. Of five plants dredged in 18 
meters off Ratones Island near Ponce, Porto Rico (mo. 7575), four 
belonged to the ‘‘Cameratae’’ and were tetrasporic, and one 
belonged to the “‘Spissae’’ and was cystocarpic. Of numerous 
plants or fragments dredged in 7-10 meters at the mouth of Guanica 
Harbor, Porto Rico (no. 7005), all of the thirteen examined 
showed the ‘‘Spissae’”’ structure, three or four of them being 
evidently antheridial, one cystocarpic, and the rest apparently 
sterile. Of five plants found washed ashore in the harbor of 
Port Morant, Jamaica (no. 6276), two had the ‘‘Spissae’’ struc- 
ture and were cystocarpic, while three showed the ‘‘Cameratae”’ 
structure, though tetraspores could actually be found on only one 
of the three. In six plants from Barbados, similar to each other 
in general habit, though not all collected at the same time and 
place, five were ‘‘Cameratae,” four of them with obvious tetra- 
spores, while the sixth showed the structure of the “‘Spissae”’ 
group and was cystocarpic. On the coast of Florida also, in the 
region of Jupiter Inlet, Indian River, and Lake Worth, in plants 
that are somewhat larger, coarser, and longer-segmented than the 
typical Galaxaura obtusata, the same correlations may be observed. 
Finally, it is to be noted by consulting Kjellman’s monograph, 
that all of the species that he placed in the group ‘‘Cameratae,”’ 
in so far as their mode of reproduction was known to him, are 
tetrasporic, while of the ‘‘Spissae’’ the one species of which the 
reproductive organs are described is cystocarpic. 
For complete proof that the ‘‘Cameratae”’ structure 1s a con- 
stant characteristic of the tetrasporic plants of Galaxaura obtusata 
and its allies and that the “‘Spissae”’ structure is likewise a constant 
character of the sexual plants, it would of course be desirable that 
