1919] Setchell-Gardner : Myxophyceae 43 



have examined shells at all seasons of the year and from different 

 localities and have not found gonidia. Tlie basal cells divide in several 

 planes into numerous small, angular cells approximating gonidia. The 

 filaments resulting from these divisions resemble those figured by 

 Bornet and Flahault (1889, pi. 11, fig. 2). The small, angular cells 

 probably escape and develop into new plants. They can hardly be 

 considered as having formed in gonidangia, because a few cells just 

 above the basal cells divide likewise though progressively to a less 

 degree, forming clavate filaments at maturity (pi. 3, fig. 19). 



3. Hyella linearis S. and G. 

 Plate 2, fig. 8 



Thalli dark blue-green, penetrating into the host, 350— 450/^ long; 

 cells of the inner ends of the filaments smallest, 4-6/x, diam., 3.5-4,5/u. 

 long, gradually increasing in size to 12ju, in diam. toward the periphery 

 of the host ; cell walls thin, hyaline ; cell divisions in one plane at first, 

 building, up more or less tortuous, rarely branched filaments ; later 

 cell divisions in three planes, often decidedly oblique, most abundant 

 toward the periphery of the host, building up clavate filaments ; goni- 

 dangia at the surface of the host, 14-20/* diam. ; gonidia numerous, 

 Ifi diam. 



Growing on Prionitis sp. Sunset Beach, near the mouth of Coos 

 Bay, Oregon. This is the type locality and only one plant of Prionitis 

 has been found infested by this species of Myxophyceae. 



Setchell and Gardner, m Gardner, New Pac. Coast Alg. II, 1918, 

 p. 442, pi. 36, fig. 8. 



This species seems closely related in form to Hyella socialis S. and 

 G., but differs principally in the size of the cells, and in having the 

 filaments nearly straight and rarely branched. The earl.y stages in the 

 development have not been observed. There is probably a prostrate 

 layer of cells developed first, characteristic of the genus Hyella, and 

 the erect penetrating filaments arise from that. The discovery of 

 Hyella socialis was made by observing the presence of small warts or 

 excrescences growing on Prionitis. Hyella was found to be uniformly 

 associated only with the warts. We presume that the presence of a 

 foreign plant may have stimulated the cells of Prionitis thus produc- 

 ing the abnormal growths at the points of infection. The rapid growth 

 of the cells of Prionitis would have the esffect of disturbing the hori- 

 zontal layer of Hyella and of dispersing its erect filaments. 



