1918J Gardmr: New Pacific Coast Marine Algae II 443 



Prianitis. Hijella was found to be uniformly associated with the 

 warts only. I presume tiiat the presence of the foreign plant stimu- 

 lated the cells of Prianitis thus producing the abnormal growths at 

 the point of infection. Tliis rapid growth of the cells of Prionitis 

 would have the ett'ect of disturbing the horizontal layer of Hyella and 

 of dispersing its erect filaments. 



Hyella socialis Setchell et Gardner sp. nov. 

 Plate 36, fig. 5 



Filamentis in hostem penetrantibus. 200-300/i, longis, tortuis, 

 dendroide ramosis, primo cellularum partitionibus in direetione una, 

 tardiore in direetionibus tribus, greges cellularum in vagina originali 

 produeentibus, grege quoque e divisione cellulae singulae oriente, 

 sicut libero, grcgibus cellularum Gloeocapsae similibus, gregibus 

 majoribus prope superficiem liostis sitis; cellulis maxime angularibus, 

 in forma magnitedineque variabilibus, 4-6/x diam., cellula terminali 

 7-9^1 longa, penetrante, maxime conica; parietibus cellularum hyalinis, 

 mollibus ; contentu cellularum laete caeruleo-viridi ; gonidangiis adhuc 

 ignotis. 



Filaments penetrating into the host. 200-300/a long, tortuous, 

 branching dendroidall}', at first cell divisions only in one plane, later 

 dividing in all directions, producing groups of cells within the orig- 

 inal sheath ; each group resulting from the divisions of a single cell 

 in tlie filament, becoming practically independent, similar to groups 

 of Gloeocapsa cells, the largest groups being nearest the surface of 

 the host ; cells very angular, irregular in shape and size, 4-6/a diam., 

 terminal penetrating cell 7-9/a long, decidedly conical; cell walls 

 hyaline, soft ; cell contents bright blue-green ; gonidangia unkno-v\ai. 



Growing on the stipitate portion of Iridaea minor J. Ag., in the 

 lower littoral belt. Carmel Bav, Monterej' County, California. Mav, 

 1916. 



The basal filaments of tlie plant, if present at all, could not be 

 thoroughly worked out with the material at hand. Further study will 

 be required to elucidate this point. A discussion of the relation 

 between the genera Hyella and Radaisia, in which the reasons are 

 stated for placing these new species as arranged here, may be found 

 on page 430 of this work. 



The early stages of the development of this species are unknown. 

 No gonidangia were present and the host plant was nearing maturity. 

 It is possible that no gonidia were developed, and that the dissolution 

 of the sheath of the groups of vegetative cells free them at the time 

 that tlic liost is beginning to disintegrate, and these vegetative cells 

 locate on vounger hosts. 



