110 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.12 



of serrate sporophylls which in young plants tend to be deeply lobed or 

 even pinnate, but in older plants are smooth, strap shaped, and show very 

 small lobes only; sori on the sporophylls, appearing as large irregular 

 fertile areas on the face of the blades. 



These are very curious plants to be found in deep water. The small 

 number of species hitherto known from the genus makes them of particu- 

 lar interest on that score also. They have a spreading fibrous holdfast, 

 from which arises in the young plant a very short, rather slender stalk 

 1-2 cm tall, terminated by a thin primary blade. This blade is broadly 

 lanceolate with a subcordate base, the margin being irregularly coarsely 

 dentate. Later, when about 2 dm tall, the blade begins to be eroded from 

 the tip and the lateral margins develop a few large divergent triangular 

 or ligulate lobes 2-5 cm long, the margins compound dentate, the first 

 coarse teeth irregular and erose, 3-10 mm long, the secondary aculeate 

 with a flattened base, about 1-2 mm long. Eventually the primary blade 

 tip disintegrates and the lateral margins of the base develop as a pair of 

 divergent incrassate flat bands 1-3 cm long from the apex of the stalk, 

 giving rise to a succession of secondary blades from the margin. First 

 formed secondary blades are commonly 1-3 dm long, linear lanceolate, 

 3-5 cm wide, erose dentate on the margins or distantly pinnately lobed, 

 the dentate lobes 5-15 mm long. Large plants at this developmental stage 

 may have blades much longer, with a midportion to 5 cm broad and lobes 

 in great excess of 7 cm long, but the specimens of this t>'pe secured were 

 all fragmentary. Mature plants appear to have 5-7 secondary blades on 

 each side and simplified blades succeed the pinnately divided blade type 

 of the 3"ounger stages. These ultimate type blades appear to be 85 cm long 

 or more, and 4-6 cm broad, the margin above irregularly aculeate serrate, 

 but below compound serrate, the lobular teeth rarely over 1 cm long. The 

 sori form large patches 3-4 cm broad and to 1 dm long or more on the face 

 of the sporophylls. The blades are thin, and adhere to paper as well as 

 most Laminariaceae of the same size. At first the subsimple sporophyll- 

 bearing specimens were thought to belong to a different species from the 

 ones with pinnately divided sporophylls. but transitions are so complete 

 as to make this conclusion unwarranted. 



The genus Eisenia was formerly composed of E. arborea of the west- 

 ern American coast, a long-stalked coarser littoral form, and E. bicyclis 

 (Kjellman) Setchell, of Japan. Later, E. Masonii Setchell & Gardner 

 (1930, p. 145, pi. 14) and E. desmarestioides Setchell & Gardner (1930, 

 p. 146, pi. 15) were added from L Guadeloupe, Baja California, Mexico. 

 In E. arborea the juvenile blades are at fii-st hardly serrate, and the mature 

 plant is larger with a heavy stalk and more numerous sporophylls. In E. 



