NO. 2 DAWSON: MARINE RED ALGAE OF PACIFIC MEXICO 259 



Grateloupia? johnstonii Setchell & Gardner 



Setchell and Gardner 1924, p. 782, pi. 84; Dawson 1944, p. 281. 



Inasmuch as no new material of this plant has been collected, little 

 can be added to our knowledge of it. However, in addition to the short 

 original description which is quoted below with corrections in typography 

 and punctuation, a statement regarding the structure of a branch of the 

 type is added. 



"Fronds flat, membranaceous, up to 40 cm. high, varying much in 

 width of the same branch in different parts, up to 2 cm. ; branching pin- 

 nate, of 5-6 orders ; ultimate pinnules short, subulate, acute, perpendicu- 

 lar to the frond; main branches arising at about 45° angle; color coral 

 red ; reproduction unknown" ; cortex of pigmented anticlinal filaments 

 of 4-5 cells arising from a subcortical or extramedullary region of loosely 

 arranged, inflated or angular cells 20-30 fi in diameter with prominent 

 interstices ; inner medulla of a loose network of mostly longitudinal fila- 

 ments of rather large diameter (10-20 ju.) ; a thin, punctate membrane 

 surrounds the cortex and separates from it when dry material is soaked 

 up. 



Type: Holotype is Johnston 88, July 1921, on sheet 1371 in the 

 Herbarium of the California Academy of Sciences, San Francisco, 

 California. 



Type locality: Cast ashore, Isla Angel de la Guarda, Gulf of 

 California, Mexico. 



The large diameter of the medullary filaments and the poor expan- 

 sion of dry sections upon soaking is unlike other Mexican grateloupiae 

 and suggests that the study of reproductive material may show that this 

 plant belongs to another genus. It will be necessary to collect fertile 

 material both of this species and of G. squarrulosa in order to clarify 

 their mutual relationship and their taxonomic position. 



Key TO THE Mexican species of Cryptonemia 

 1. Blades usually simple though sometimes lobed or lacerate . . 2 

 1. Blades distinctly and repeatedly branched 4 



2. Blades to 7 cm. broad, 100-200 /a thick . . C. obovata 



2. Blades less than 2 cm. broad, less than 100 fx thick ... 3 



3. Blades entire, 35-60 fx thick C. angustata 



3. Blades early splitting and becoming much lacerated, 80-90 /* 



thick , C. veleroae 



4. Blades divaricately dichotomously branched ; margins entire 

 or undulate C. guciymasensis 



