146 COLLINS AND HERVEY. 



inclusa; uno, raro duobus ad nodum, corticatione fere liberis, secun- 

 dum ramum longitudinaliter seriatis. Plate V, figs. 29-31. 



Minute, creeping over other algae or rocks; prostrate filaments 

 60-90 /JL diam., cells 1^-8 diam. long, cylindrical or slightly con- 

 stricted at nodes, attached by colorless, unicellular rhizoids issuing 

 one or more at a node; an erect branch occasionally issuing at a node; 

 apex of prostrate filament becoming erect and similar to an erect 

 branch; penultimate branches about 60 ju diam.; cells in erect part 

 not over 2 diam. long, near the apex less than one diam.; repeatedly 

 forking; lower cells cylindrical, upper apparently very shortly clavate 

 by the growth of cortication at the upper end; cortication sharply 

 marked off from uncorticated portion, the lower portion of each band 

 showing a series of transversely elongate cells passing around the 

 central cell ; the upper part of 2-3 series of irregularly placed roundish- 

 angular cells. Protoplast uniformly granular, or with slender, paral- 

 lel, longitudinal striations the whole length of the cell; the protoplast 

 cylindrical in the lower cells, subspherical in the upper. Cystocarp 

 borne at the end of a segment of 2-5 cells, which increase in size up- 

 ward, the upper cell being twice the diam. of the lower or even more; 

 on this are borne several wide-spread, few-celled involucral branches 

 with one or two cystocarps between them, the cystocarps appearing 

 terminal, but with usually an axis extended beyond them and the 

 involucre, of few cells, the basal cell 2-3 diam. long, the others, as all 

 the cells in the involucre, hardly 1 diam. long. Tetrasporangia tri- 

 partite, up to 60 ju diam. not including the wall 8 (JL thick; one, occa- 

 sionally two at a node, in longitudinal series, nearly free from the 

 cortication. 



On Galaxaura, Spanish Rock, April 10, 1914, Hervey, type in 

 Collins herbarium, No. 8107. Also occurring on Zonaria variegata, 

 Harrington Sound, May, on Padina variegata, Agar's Island, Nov., 

 on Thalassia, Fairyland, Dec., Collins; on Ascothamnion, Tucker's 

 Town, July, Howe. 



The peculiar form of cortication, from which we have taken the 

 specific name, does not seem to occur in any other species. C. minia- 

 tum Suhr, resembling it in some respects, has distichous branching, and 

 small tetrasporangia sessile on both sides of the branches. Specially 

 characteristic of C. transversale are the serrate outlines near the apices, 

 due to the sharp limitation of the cortical growth there, and the tetra- 

 spores unusually large in proportion to the size of the frond. When two 

 tetrasporangia are formed at a node, they are set side by side, the line 

 made by the series of single sporangia passing between them. The 



