52 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



3. Filaments free, or somewhat twisted together, but not united 



into cords by special branchlets Cladophora 



3. Filaments in the lower part of the plant united by rhizoidal, 



hooked or spinelike branchlets Spongomorpha 



GHAETOMORPHAKutzing, 1845 



Plants filamentous, the filaments uniseriate, unbranched ; cells cylin- 

 drical or slightly inflated, with numerous peripherally placed nuclei and 

 a much-dissected chromatophore with many pyrenoids; plants attached 

 by a basal cell, which may be well marked in form, or unattached and 

 with no evidence of holdfasts. 



KEY TO SPECIES 



1. Plants definitely attached, and forming erect tufts .... 

 C. antennina 



1. Plants entangled, without definite point of attachment . . 2 



2. Plants with filaments commonly under 200 /* diam., the cells 

 generally shorter than their width . C. brachygona v. crassipellita 



2. Plants with filaments reaching 300 /a, the cells 1.7-3.0 diameters 



long, seldom shorter C. Linum 



Ghaetomorpha antennina (Bory) Kiitzing 



Plants attached, gregarious, the filaments rather firm and more or 

 less erect, to 16 cm tall; the hapteron consisting of branched rhizoidal 

 extensions arising at various levels on the lower part of the basal cell; 

 basal cell notably distinct, clavate, to 6-10 mm long (reported to 15 mm), 

 the lower part tapering and about 100-150 ju, diam. in the hapteral region, 

 commonly rugose above it and near the top of the cell 450-580 ju, diam. ; 

 cells slightly cask shaped, the lower cells of the axis about 530-560 fi 

 diam., 1.5 mm long, the upper cells 450-650 p, diam., about as long as 

 broad, more markedly cask shaped. 



Howe 1914, p. 37; B0rgesen 1940, p. 37. 



This species takes the place of C. media (C. Agardh) Kiitzing (Tay- 

 lor 1942, p. 22) found in the Caribbean in similar situations. The longer 

 basal cell seemingly has its rhizoidal extensions scattered rather than, as 

 in C. media, in a limited, almost discoid, group. This distinction, like 

 others which have been suggested, may not suffice to maintain these as 

 distinct species. Howe (1914, p. 37) states that the basal cell as figured 

 by Kiitzing (1853, p. 19, pi. 60, by mistake labeled on the plate as C. 



