88 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



tapered to the margins; ultimate segments with irregular, closely set, 

 ascending, falcate pinnae; growing tips acute, with an apical cell; in- 

 ternal structure in median and older parts consisting of a large central 

 axial filament 70-90 fx. in diameter, and two or more similar filaments 

 usually confined to the median line, within a broad medulla densely 

 packed with secondary, more or less longitudinal, rhizoidal filaments, 

 except just beneath the cortex where two or more layers of subspherical 

 cells 15-25 fi in diameter are usually not densely invaded by the fila- 

 ments; cortex of 2-3 layers of densely pigmented small cells, the outer- 

 most anticlinally elongated, 5-7 ju. long; tetrasporangia unknown; cysto- 

 carps (not observed in Mexican material) 150-350 fj. in diameter, ir- 

 regularly reniform, embedded, aggregated in the swollen tips of ultimate 

 branches, without a distinct ostiolar opening. 



Type: Holotype is a collection by Captain Pike in the Harvey 

 Herbarium, Trinity College, Dublin, Ireland. 



Type locality: Golden Gate [San Francisco], California. 



Mexican distribution: Pacific Baja Calif. — D. 1302, Punta 

 Baja, Apr. 



This species is usually distinguished macroscopically from the similar 

 Leptocladia binghamiae by its more slender proportions, particularly in 

 lower parts, and its usually denser, more bushy branching. Undoubted 

 specimens of L. binghamiae^ however, have been examined which are just 

 as slender and just as densely branched as normal P. calif arnica. Hence, 

 macroscopic characters do not suffice. The cystocarps of Pikea calif ornica 

 are aggregated in the swollen ends of the narrow, ultimate branches, un- 

 like the scattered ones of L. binghamiae. Structurally P. calif ornica seems 

 consistently to show several large central filaments in addition to the 

 primary central axial filament, while L. binghamiae shows only the 

 latter. This is true on account of the many more branches of the second 

 order in P. calif ornica. 



Dr. Isabella Abbott, in a critical study of Pikea and Leptocladia (as 

 yet unpublished) has concluded that Esper's Fucus nootkanus is not 

 equivalent to Pikea californica Harvey.^ Her studies also have led her 

 to differ further from Doty in excluding Leptocladia conferta from 

 synonymy with P. californica. I am inclined here to follow Abbott in 

 anticipation of the appearance of her report. 



The specimens from Isla Cedros and Cabo Colnett, Baja California 

 referred to Pikea nootkana by Dawson, 1949, although in part very 

 slender and much branched above, seem by their structure to agree 

 better with Leptocladia binghamiae. 



1 Silva, in a paper yet unpublished, identifies Fucus nootkamis Esper with 

 Bonnemaisonia californica Buffham. 



