NO. 2 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 257 



arachnoid, grading into the pigmented cortex of anticlinal filaments of 

 4-5 small cells; tetrasporangia cruciate, scattered through the cortex 

 just below the surface, 30-35 /a long, 10-12 /x wide; carpogonial branch 

 systems separate from auxiliary cell systems; gonimoblast development 

 apparently as in G. filicina; cystocarps embedded in the broader upper 

 branches, scattered or more or less aggregated ; antheridia in a continu- 

 ous, superficial layer, borne on cortical filaments showing little nema- 

 thecial modification. 



Type: Holotype not designated, but represented by Liebmann's 

 original collection in the Agardh Herbarium, University of Lund, 

 Sweden. 



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



Mexican distribution: Baja Calif, del Sur — D. 6716, Isla 

 Magdalena, Mar.; D. 6761, Cabeza Ballena, Mar.; Sinaloa — D. 3597, 

 Mazatlan, Dec. Guerrero — Taylor 576-34, Bahia Petatlan, Mar. 

 Oaxaca — D. 3775, Salina Cruz, Jan. 



A collection seemingly in agreement with the Mexican specimens is 

 also at hand from warm pools at La Jolla, California. 



Grateloupia dactylifera sp. nov. 

 PI. 10, fig. 53 



Thallis dumum laxum rotundum ad 4 cm. altum, 6 cm. latum form- 

 antibus, ubique complanatis; ramificatione dichotomoflabellata, divar- 

 icata, ad ultimum dactyloidea ; segmentis brevibus ad 2.5 mm. latis prope 

 basim, ad ultimum acutis ac minoribus quam 1 mm. latis, 200-300 ju. 

 crassis. 



Thallus to 4 cm. high and 6 cm. broad, in the form of a loose, 

 rounded clump, complanate throughout, 200-300 jx thick, consisting of 

 1 to several substipitate or sessile, dichotomous, much-branched fronds 

 from a small irregular disc; branching dichotomo-flabellate, divaricate, 

 ultimately dactyloid, the segments very short, broadest near the base 

 (to 2.5 mm.), ultimately acute and less than 1 mm. broad; transection 

 showing a moderately dense to loose medulla of mostly longitudinal 

 filaments about 5 /x in diameter, a ± indefinite subcortex of angular to 

 arachnoid cells, and an outer cortex of anticlinal filaments of 3-4 small 

 cells about 3-4 fi broad, the outer 2-3 pigmented; cystocarps embedded 

 in the thallus on either side, about 120-130 /a in diameter, ostiolate, most- 

 ly aggregated on segments near the outside of the clump; carpospore 

 mass subglobose to reniform, pedicellate on the modified auxiliary cell; 

 carpospores about 14 /x, in greatest diameter; tetrasporangia and anther- 

 idia not seen. 



