196 BROOKLYN BOTANIC GARDEN MEMOIRS 
representing a single species, as in all probability they do, even though 
the current system of classification would require us to put them not 
only in different species-covers, but also in different sections of the 
genus. Likewise, in Bermuda, these two forms, Galaxaura flagelli- 
formis and G. squalida, occur and in one instance, at least, they haye 
been placed together under one field number by F. S. Collins (8486 
‘in herb. N. Y. Bot. Gard.). 
In a similar way, Galaxaura subverticillata Kjellm., a tetrasporic 
plant representing the section ‘‘Rhodura,” and G. rugosa (Ell. & Sol.) 
Lamour., a sexual plant representing the section ‘‘ Microthoé,”’ are, 
in all probability, phases in the life-cycle of one and the same species. 
As instances of their occurrence together may be mentioned the 
writer’s no. 2042 (Santurce, Porto Rico), in which the two, the G. 
subverticillata with young tetrasporangia and the G. rugosa with cysto- 
carps, were found intertangled in the same tuft; the writer’s nos. 
7470 (G. subverticillata) and 7469 (G. rugosa), growing close together 
and sometimes intermingled, near the low-water line on Muertos 
Island (Caja de Muertos), Porto Rico; the writer’s no. 4909a, G. 
subverticillata, tetrasporic, occurring with or near no. 4911, G. rugosa, 
cystocarpic, and other forms of Galaxaura at Montego Bay, Jamaica. 
It must be confessed, however, that G. subverticillata occurs also with 
sexual plants that agree more closely with G. squalida than with G. 
rugosa and that just as the lines of distinction between G. flagelliformis 
and G. subverticillata often seem vague and uncertain, so also do G. 
squalida and G. rugosa appear to intergrade. 
The plants included by Kjellman in his section “‘Eugalaxaura”’ 
appear to be all sexual, never tetrasporic. The cortex is here smooth 
and firm, much as in the section ‘‘ Microthoé,’’ but the epidermal cells 
are commonly smaller, the cortex dissolves into its constituent fila- 
ments more readily on decalcification, the thallus is more distinctly 
jointed, and free superficial assimilatory filaments are of less frequent 
occurrence. The tetrasporic phases of the “ Eugalaxaura’’ forms are 
apparently to be found in the section ‘ Rhodura,”’ this section supply- 
ing the tetrasporic conditions for both the section ‘“‘Microthoé”’ and 
the section ‘Eugalaxaura.’”’ From size and association (at Santurce, 
Porto Rico, and elsewhere) more than from any similarity in habit (for 
the two are, as a rule, strikingly different in habit), the writer believes 
that Galaxaura cylindrica (Ell. & Sol.) Lamour. of the section ‘‘ Euga- 
laxaura’”’ finds its tetrasporic phase in G. lapidescens (Ell. & Sol.) 
Lamour., of the section ‘‘Rhodura,” as this species has been recently 
limited and defined by Bérgesen.> And, with less assurance, it may 
5 Mar. Alg. Dan. W. I. 2: 95-99. f. 102-104. 1916. 
