402 University of California PiMications in Botamy [Vol. s 



are represented by species occurring within our territory, but Bache- 

 lotia does not seem to have been detected here as yet. The subgenus 

 EiipylaieUa, whose species are distinguished by their comparatively 

 more frequent opposite or alternate branching, is founded naturally on 

 Pylaiella littoralis, some forms of which are very tall, but also includes 

 low forms, such as P. curta Foslie and P. nnilateralis S. and G. Bache- 

 lotia and Panthocarpus, whose erect filaments are either unbranched 

 or sparsely branched, include only forms not over three centimeters in 

 height. In Eupylaiella, and probably also in Bachelotia (known cer- 

 tainly only with zoosporangia) , the gametangia develop simultaneously 

 throughout the series which is, therefore, limited and definite. In 

 Panthocarpus, the gametangia develop successively and from above 

 downward. Further and more careful study of gametangial develop- 

 ment in a large series of forms and species is necessary to fully sustain 

 these statements. 



Key to the Species 



1. Branching frequent, opposite, alternate or secund — (Eupylaiella) 2 



1. Branching none or sparse and opposite — (Panthocarpus) 3 



2. Upper branches opposite or alternate 1. P. littoralis (p. 402) 



2. Upper branches regularly secund 2. P. unilateralis (p. 404) 



3. Plants up to 15 mm. high, simple or with opposite ramuli above 



3. P. Gardneri (p. 405) 



3. Plants not over 1 mm. high, simple 4. P. tenella (p. 406) 



1. Pylaiella littoralis (L.) Kjellman 

 Plate 37, fig. 32 



Erect assimilatory filaments very profusely branched, either densely 

 caespitose or funiculate, 2 cm. to 6 dm. hig'h, creeping filaments richly 

 branched, somewhat irregular in diameter ; color varying from light 

 yellowish brown to dark brown; primary filaments 20-60jti diam., cells 

 1-6 times as long as the diameter, ramuli more slender, opposite or 

 alternate, strict, patent or even at times recurved, short and subulate 

 or long and gradually attenuated, occasionally pilif erous ; zoosporangia 

 in each series mostly formed simultaneously, 5-25-catenate, usually 

 one in each joint, rarely 2-4 formed by longitudinal divisions of a 

 single cell, intercalary or terminal, varying in shape from oblate to 

 prolate spheroidal, 25-45/x diam. ; gametangia intercalary, in a con- 

 tinuous series up to ISOOju, long, 20-35ju, diam. ; zoosporangia and game- 

 tangia usually on separate plants, but occasionally on the same plant. 



Growing on other algae, on rocks and on wood in the littoral belt. 

 Bering Sea to southern California (San Pedro). 



