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 have 

 been placed together under one field number by F. S. Collins (8486 

 in herb. N. Y. Bot. Card.). 



In a similar way, Galaxaura suhverticillata Kjellm., a tetrasporic 

 plant representing the section "Rhodura," and G. rugosa (Ell. & Sol.) 

 Lamour., a sexual plant representing the section "Microthoe," 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. 

 suhverticillata with young tetrasporangia and the G. rugosa with cysto- 

 carps, were found intertangled in the same tuft; the writer's nos. 

 7470 {G. suhverticillata) 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. 

 suhverticillata, tetrasporic, occurring with or near no. 491 1, G. rugosa, 

 cystocarpic, and other forms of Galaxaura at Montego Bay, Jamaica. 

 It must be confessed, however, that G. suhverticillata 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. suhverticillata 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 "Microthoe," 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 "Microthoe" 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 Bprgesen.'^ And, with less assurance, it may 



^ Mar. Alg. Dan. \V. 1. 2: 95-99./. 102-104. 1916. 



