19-^] SetcheU-Gardner: Melanophyceae 707 



Lepidium Rupreclit, Tange Oeliot. Meeres, 1851, p. 347 ; Collins, 

 Holden and Setchell, 'Phyc. Bor.-Amer. (Exsicc), no. XLVII. Cysto- 

 seira gemimita Agardh, Syst. Alg., 1824, p. 286. 



Since publishing our account in the Algae of Northwestern 

 America, we have not been able to secure any additional data by which 

 to separate the four species of the genus Cystaphyllum, accredited to 

 our region and which we united into one species under the foregoing 

 combination. 



71. Halidrys Lyngb. 



Plants consisting of a solid holdfast, a stipe, flattened and terete 

 fronds ; the flattened fronds alternate on the stipe, these metamorphos- 

 ing into pinnately branched filiform branchlets; cysts in a series, 

 developing in the flattened fronds, leaving a margin on either side of 

 the series; these fronds terminating in branched receptacles; one egg 

 cell in each oogonium ; monoecious or dioecious ; perennial, the fruiting 

 fronds dying back to the stipe each year. 



Lyngbye, Hydrophyt. Dan., 1819, p. 37. 



But two species of this genus, as restricted by Greville (Alg, Brit., 

 1830, p. xxxiv), are at present known, H. siliquosa (L.) Lyngbye, on 

 the Atlantic coast of Europe, and the following species on the coast 

 of southern California. 



Halidrys dioica Gardner 



Stipe arising from a flattened, solid, warted ba.se, terete, bent at the 

 "nodes," 40-50 cm. long, 4—6 mm. diam., solid, flexible, not forked; 

 primary pinnae annual, arranged alternately upon the stipe, always 

 arising just below the growing point, 10-18 dm. long, flat and linear 

 at the base, pinnately branched above, the linear portion 10-25 cm. 

 long, 8-12 mm. wide ; secondary branches or pinnules sessile, flat, acute 

 or obtuse at the apex, the oldest ones entire, the younger ones variously 

 notched and incised, the incisions increasing in depth, and the seg- 

 ments increasing in length toward the apex of the branch, the upper- 

 most becoming pinnately branched ; the upper secondary branches 

 develop flattened, margined, lanceolate, acuminate, short pediceled air 

 vesicles, divided into 5-9 chambers, slightly constricted at the divi- 

 sions, the oldest rounded at the base and mucronate at the apex ; the 

 apex of the younger ones developing farther into branched filiform 

 receptacles and these in turn bearing many conceptacles ; plants peren- 



