156 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



Gelidium sclerophyllum n. sp.^^ 

 Plate 5, Fig. 13 ; Plate 33, Fig. 2 



Plants small, from a creeping base erect 1-2-pinnate branches arising 

 to 1-3 cm in height, the linear branches compressed above to 0.5 mm in 

 width, terete below, texture corneus; in transverse section showing a row 

 of large very thick-walled cells spaced at intervals across the width of 

 the blade, these separated and surrounded by close-packed rhizines which 

 become more scattered in the inner cortex where the colored cells appear, 

 but no large thin-walled cells present in the medulla; tetrasporangia, 

 young and old intermixed, occupying the central area of small stipitate 

 lateral or terminal branchlets, the margin sterile and thicker when dry, 

 the tips deeply indented; cystocarps generally near the ends of acute- 

 tipped lateral branches, bilocular with a median septum and swollen on 

 both faces. 



This little plant shows most extraordinary sectional structure for the 

 genus. It is one of several which make the histological distinction between 

 Pterocladia and Gelidium a character which is, when considered alone, 

 often undecisive. Howe's G. caloglossoides (1914, p. 96, pi. 34, fig. 7, pi. 

 35 ) shows structural similarity, but quite different branching habit. 



Costa Rica: Golfo Dulce, on the under side of rocks, stunted, no. 

 39-99, 26 Mar. 1939. Ecuador: Esmeraldas, dredged in 5.4 meters of 

 water with corallinae near the northeastern side of Ba. San Francisco, 

 no. 34-489 (cystocarpic and tetrasporic, TYPE), 11 Feb. 1934. Guayas, 

 Pta. Santa Elena, Schmitt no. 517, 17 Sept. 1926. 



Gelidium densum Gardner 



Gardner 1927, p. 278, pi. 47, fig. 1, pi. 48. 



These plants are somewhat smaller, more delicate, and more dense in 

 the terminal branching than Gardner illustrates, but are interpreted as 

 an extreme form of the species. Rhizines were clearly present in the sub- 

 cortex. 



Mexico: Baja California, on the shore of South Bay, I. Cerros, no. 

 34-640, 10 Mar. 1934. 



92 Gelidium sclerophyllum n. sp. — Plantae parvae, rhizomatosae, ramis erectis 

 1-2-pinnatis, 1-3-cm altitudine, linearibus, supra compressis, ad 0.5 mm lat., infra 

 teretibus, textura corneis; tetrasporangiis centrum ramulorum parvorum, lateralium 

 aut terminalium, stipitatorum occupantibus, cacuminibus profunde indentatis, 

 marginibus sterilibus; cystocarpis bilocularibus plerumque prope partes extremas 

 ramorum lateralium acuminatorum. Planta tvpica in loco dicto Ba. San Francisco, 

 Esmeraldas, Ecuador, legit W. R. Taylor no'. 34-489, 11 Feb. 1934. 



