NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 311 



Type: D. 441, middle littoral, on Laurencia, San Esteban Island, 

 Feb. 5, 1940. Herb. AHF no. 51. 



D. 283, on Corallina in a water-filled rock-cup at low tide, Puerto 

 Refugio, Jan., D. 219, on Amphiroa at same locality. 



This species differs from other allied species of Champia in its small 

 size, its strongly compressed nature, and distichous branching. 



Champia caespitosa sp. nov. 

 Plate 46, Figs. 3, 4 



Frondes plerumque epiphyticae, circa 2 cm. altae, caespites parvas ramorum 

 intertextorum et per rhizinas connectas ostendentes et basi ad substrata algarum 

 per rhizinas disciferas irregulares affixae, copiose multifarie ramosae, leviter com- 

 pressae, 500 x 900 \i in sectione transversali ; segmentis circa quam latis quam 

 longis. 



Plant colonies mainly epiphytic, about 2 cm. high, forming small 

 caespitose mats of intergrown and rhizoidally joined branches, from sev- 

 eral basal attachments to algal substrata by irregular, rhizoidal disks; in- 

 dividual plants almost indistinguishable because of the numerous acces- 

 sory holdfasts which interlock the various parts ; fronds abundantly short- 

 branched from all sides, hollow, slightly constricted by regular dia- 

 phragms into segments usually about as long as broad, slightly compressed, 

 the dimensions about 500 by 900 /a in cross section, composed of a single 

 cortical layer of axially elongated cells here and there interspersed with 

 smaller irregularly shaped cells within, and attached to which is a series 

 of longitudinal gland-cell-bearing filaments ; gland cells sometimes occur- 

 ring also on the inner surface of the cortical cells ; rhizoidal attachments 

 abundantly formed by means of surface cell elongation and division ; cys- 

 tocarps and tetrasporangia unknown ; color bluish, iridescent when fresh. 



Type: D. 407, rocky shore, middle littoral, on articulated coral- 

 lines, Pond Island, February 4, 1940. Herb. AHF no. 52. 



D. 193a, on Digenta, D. 212a, on Centroceras, Puerto Refugio, Jan. 

 (fragmentary). 



This species in general form and structure resembles C. parvula rather 

 closely, but in habit is very distinct. The abundant production of acces- 

 sory rhizoidal holdfasts causes the plant colony to assume a compact, caes- 

 pitose, distinctly matted aspect, which is augmented by the relative rigid- 

 ity of the branches as compared to C. parvula. The branches differ from 

 the generally more extended, looser ones of C. parvula by their shortness 

 and more erect habit. C. parvula, moreover, generally has cylindrical 

 fronds, while those of this species are slightly compressed. 



