26 THE HANCOCK PACIFIC EXPEDITIONS VOL. 3 



chlor-zlnc-iodine. Like the typical variety, it is epiphytic on other 

 algae, and at least in early stages of growth can be seen attached 

 to the substratum otherwise than by a basal cell. The sheaths, as 

 the authors of P. monile assert, are "conspicuous, . . . distinct, not 

 diffluent." Such characteristics are so pronounced in our material 

 and in the type specimen that we cannot find justification for retain- 

 ing in the genus Phormidium this form so closely related morpho- 

 logically to Lyngbya gracilis. Phormidioid layers of parallel filaments 

 of many long-established species of Lyngbya are often encountered 

 where the filaments are numerous or where the plant mass is ex- 

 posed at times to the atmosphere. 



Lyngbya semiplena (C. Agardh) J. Agardh ex Gomont, Ann. 

 Sci. nat. VII, Bot. 16: 138. 1892. 



Forma trichomatibus 7/x ad 7.5/j, crassis. Fig. ij. 

 MEXICO: Revilla Gigedo Islands, rare and mixed with Hydro- 

 coleum comoides, etc., in high warm tide pools, Sulphur Bay, Clarion 

 Id., No. 65, January 5. 



Lyngbya versicolor (Wartmann) Gomont, Ann. Sci. nat. VII, 

 Bot. 16: 147. 1892. 



Forma fills intricatis tortuosisque; trichomatibus ad genicula hand 

 aut non constrictis, dissepimentis pellucidis, non granulatis; articulis 

 plus minusve 3/x. crassis, ad 6/x longis; vaginis hyalinis, chlorozincico 

 iodurato caerulescentibus, ad 2/a crassis. Fig. 6. 



ECUADOR: Galapagos Islands, bottom muck in the center of 

 an inland salt pool, north end of Isabela Id., near Albemarle Point, 

 No. 123, January 12. 



OsciLLATORiA laetevirens Crouan ex Gomont, Ann. Sci. nat. VII, 

 Bot. 16: 226. 1892. 



A forma typica protoplasmate hand luteolo sed pallide aerugineo- 

 caeruleo difFert. Fig. 5. 



MEXICO: Revilla Gigedo Islands, forming blue-geen strata 

 on Calothrix pilosa 'drifted ashore,' Sulphur Bay, Clarion Id., No. ^y, 

 January 5. 



The lack of the characteristic yellowish-green color of the proto- 

 plasm is due probably to the method of drying the material; however, 

 the shapes of the cells are beautifully preserved. 



