36 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



Except for a somewhat less dense filamentous medullary region and 

 somewhat more bulbous terminal cells of the peripheral filaments, these 

 plants are indistinguishable from the Japanese species. Unfortunately 

 they are sterile and confirmation of this determintion must await the 

 collection of reproductive material. They are also structurally similar to 

 Nemalion virens which has similar bulbous terminal cells of the peri- 

 pheral filaments. The medullary filaments as well as the peripheral fila- 

 ment cells in that species are of smaller diameter, and the entire plant is 

 taller and less densely branched. 



Nemalion virens J. Agardh 

 Plate 1, fig. 4 



J. Agardh, 1847, p. 8; J. Agardh, 1852, p. 420; B(^rgesen, 1942, 

 p. 27. 



Thalli to 7.5 cm. high, consisting of several repeatedly dichotomously 

 branched erect parts from a small basal attachment; branch angles nar- 

 row ; segments 4-6 mm. long throughout, or sometimes reduced to about 

 2 mm. near the apices, up to 2 mm. in diameter just above the base and 

 in mid-parts, gradually attenuated to 350-400 [x, the tips blunt; thallus 

 composed of a central, loose, axial tissue of branched, interlaced filaments 

 3.5-4.5 fjL in diameter giving rise to a subcortex of gross filaments of large, 

 colorless, irregularly shaped cells from which arise groups of short, 

 branched, chromatophore-bearing peripheral filaments of the cortex; pig- 

 mented peripheral filaments moderately compact, consisting of series of 

 2-3 cells, the lower one or two narrow-elongate, much smaller than the 

 bearing subcortical cell, the terminal one appearing inflated, ovate, to 

 10-12 fx. in diameter; antheridia borne in whorled tufts on the sub- 

 terminal cells of the peripheral filaments. 



Type: Holotype is a collection by Liebmann on sheet 54018 in the 

 Agardhian Herbarium of the Botanical Museum, University of Lund, 

 Sweden. An isotype is in the Botanical Museum, Copenhagen, and iso- 

 type slides are in HAHF. 



Type locality : Punta San Agustin, Oaxaca ?, Mexico. 



Mexican distribution: Baja Calif. — D. 3341, Cabeza Ballena, 

 near Cabo San Lucas, Nov. 



The Baja California material shows convincing identity with the 

 Liebmann type. The species is distinctive in its abundant, regularly 

 spaced dichotomous branching, its size and pale yellowish green color. It 

 shows some structural similarity to Nemalion pulvinatum. 



