290 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 3 



gati'on was evidently first made after a study of the species of this genus 

 reported by these same authors in 1937. Re-examination of these plants 

 confirms the statement. 



Only a single fragmentary specimen has appeared in recent Gulf col- 

 lections, but is easily identified here. 



The species was first collected by Johnston in beach drift on San 

 Pedro Martir Island, April. Our present plant was taken in a 4-30-meter 

 dredge-haul off Tiburon Island near Turner's Island, D. 140, Jan. 



Sarcodiotheca dichotoma (Howe) comb. nov. 



Anatheca dichotoma Howe, 1911, p. 502, pi. 29. 



This species was described and illustrated sufficiently by Howe to be 

 recognized readily. Its widely divaricate, dichotomous branching is a con- 

 spicuous distinguishing feature. Other Pacific coast species are definitely 

 stricter in habit. 



The type specimens were from La Paz, Vives lie, 18b, 20a. Abun- 

 dant sterile material has been obtained from 30-36 meters in Ensenada de 

 San Francisco near Guaymas, D. 471, Feb. 



Family Hypneaceae 



Genus HYPNEA Lamouroux 

 Hypnea nidifica J. Ag. 



J. Agardh, 1852, p. 451; 1876, p. 564. Hypnea Marchantae Setch. & 

 Gard., 1924, p. 759, pi. 23, figs. 22, 23, pis. 42a, 56. 



This species was originally described from Hawaii, and an investiga- 

 tion of Hawaiian Hypneae has convinced me that it is distinct from other 

 species of that region. In the Herbarium of the University of California 

 there is a fine collection of Hawaiian material containing a good number 

 of specimens of Hypnea nidifica. Its loose divaricate branching is conspicu- 

 ously different from the more percurrent growth of the other species. We 

 can indeed be quite certain that we have abundant, typical material of 

 this species, showing a broad range of variation. 



Hypnea nidifica varies widely in size, but the divaricate branching 

 habit, quite devoid of percurrent axes, is generally consistent. A gradual 

 transition in size of branches is found among the specimens on hand, and 

 in the coarser ones the number of stichidia is greater. A comparison of the 

 type of H. Marchantae from the Gulf with coarser specimens from Ha- 



