NO. 1 DAWSON: MARINE RED ALGAE OF PACIFIC MEXICO 83 



growing material usually with three hairs) ; tetrasporangia disposed in 

 two rows along the axis of determinate branchlets; sexual plants not seen. 



Type : A collection by Liebmann in the Agardh Herbarium, Lund, 

 Sweden. 



Type locality: San Agustin, Mexico (presumably along the 

 coast of Oaxaca in the Isthmus of Tehuantepec region). 



Mexican distribution: Gulf of Calif. — D. 325-40, Bahia Gon- 

 zaga; D. 392-40, Bahia Tepoca; D. 406b-40, Isla Pond; D. 540a-40, 

 Bahia Agua Verde; D. 978, Isla Tiburon; D. 18948a, Isla Espiritu 

 Santo; D. 10891, 10908, Bahia Topolobampo. 



Several of these materials are in good growth and show a frequent 

 to regular development of the three terminal hairs. However, D. 978 is 

 apparently somewhat dwarfed or stunted and shows only single apical 

 cells or hairs, or, occasionally, tips with two hairs, but not three. 

 Standing alone this plant might well be placed in Taenioma macrourum 

 Thuret according to the interpretation of Tseng 1944, but in D. 10891 

 one can find in almost every slide field of the material tips with one, 

 two and three hairs, so that it is difficult to accept the number of 

 terminal hairs as a basis for distinguishing these two species. 



Sorella delicatula (Gardner) Hollenberg 

 PI. 34, fig.2 

 Hollenberg 1943, p. 577. Erythroglossum delicatula Gardner 1926. p. 208. 

 pi. 18. Sorella delicatula var. californica Hollenberg 1943, p. 577, fig. 13-14. 

 Erythroglossum divaricatum Gardner 1926, p. 207, pL 17. fig. 2. is probably 

 included here but fertile material is needed for verification. 



Thalli 1-2 cm. high (sometimes up to 10 cm. in quiet, deep water), 

 mostly dichotomo-flabellately branched, the flattened divisions 200-500 

 (600) ji broad; margins smooth; blades monostromatic except at the 

 inconspicuous midrib ; tetrasporangia sori oval, 200-400 /x broad, usually 

 solitary in the center of branches near the ends; cystocarps 400-450 /x 

 in diam., occupying nearly the entire width of branches; spermatangial 

 sori occurring singly as irregular oval patches at the very tips of the 

 branches. 



Type: Mrs. H. D. Johnston 139, June 1899, in Herb. University 

 of California Berkeley (94715). 



Type locality: Washed shore, San Pedro, California. 



Mexican distribution: Pacific Baja Calif. — D. 4226, on a Halio- 

 tus shell from 4 m., east side of Isla Coronado del Norte. 



Recent collections of this plant have shown that the type specimen 

 probably represents a maximum development of stature in a deep-water 

 plant, while most materials collected at lowest tide levels are dwarfish 

 plants only 1-2 cm. high. Experience with this and other related genera 

 indicate that these size differences are related directly to the local en- 

 vironment and usually reflect the amount of agitation under which the 



