442 University of California Puhlications in Botany [Vol. 6 



been observed. Goiiidangia may not develop, and reproduction may 

 be wholh" vegetative in the same manner that vegetative reproduction 

 is reported to occur in H. caespitosa. I base my opinion on the fact 

 that I have examined shells at all seasons of the year and from 

 different localities and have not found gonidia. The basal cells divide 

 in several planes into nvimerous small angular cells, approximating 

 gonidia. The filaments resulting from these divisions, resemble those 

 figured by Bornet and Flahault (1889, fig. 2). These small, angular 

 cells possibly escape and develop into new plants. They can scarcely 

 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. 37, fig. 19). 



Hyella linearis Setehell et Gardner sp. nov. 

 Plate 36, fig. 8 



Thallis dense caeruleo-viridibus, in hostem penetrantibus, 350- 

 450/i, longis ; cellulis finium filamentorum internorum minimis, 4-6/a 

 diam., 3.5-4.5//. longis in magnitudine ad 12/i, diam. supra superficiem 

 externam hostis augentibus; parietibus cellularum tenuibus, hyalinis. 

 partitionibus cellularum prima in directione una, filamenta plus 

 minusve tortua et sparse ramosa f ormantibus ; tardiore partitionibus 

 cellulis in directionibus tribus, frequenter maxime obliquis, fre- 

 quentissime ad superficiem hostis filamenta clavata formantibus ; 

 gonidangiis in superficie hostis sitis, 14-20/i, diam. ; gonidiis numerosis, 

 1^ diam. 



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

 cells of the inner ends of the filaments smallest, A—G/x diam., 3.5-4.5/t 

 long, gradually increasing in size to 12ix 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 in Prionitis sp. Sunset Beach, near the mouth of Coos 

 Bay, Oregon. May, 1914. This is the type locality and only one plant 

 of Prionitis has been found infested by this species of Myxophyceae. 



This species seems closely related in form to Hyella socialis of this 

 paper, but differs principally in the size of the cells, and in having 

 the filaments nearly straight and rarely branched. See the discussion 

 on page 430 of this paper concerning other species of this genus touch- 

 ing on this point. I was led to the discovery of Hyella linearis by 

 observing the presence of small warts, or excrescences growing on 



