1918] Gardner: New Pacific Coast Marine Ahjuc II 44 < 



developed (pi. 37, fig. 13). The cell walls of this basal layer are 

 transparent, seem to be gelatinous, so that the cells soon become more 

 or less freed and independent of each other. Horizontal divisions 

 begin and short filaments, 3-5 cells long, are formed above the surface 

 of the host. Meanwhile it seems possible that the prostrate layer has 

 begun to dissolve the cuticle and the underlying cortical cells, and 

 division of the basal cells may have begun forming filaments which 

 push into the host completely dissolving the host cells as they penetrate 

 (pi. 37, fig. 12). 



The plants upon which this species is founded are scarcely mature, 

 the gonidangia being very rare. Tlie deptli to which they may pene- 

 trate the host is thus rather uncertain. It is not at all unlikely that 

 they may penetrate to a much greater deptli than that reported in 

 the diagnosis above. It certainly seems that the whole of the cells 

 of the host is actually absorbed, or at least destroyed, as far as the 

 parasite travels. 



Rad-aisia suhimmersa may be looked upon as being on the border 

 line between Radaisia and Hyella so far as its relation to the host is 

 concerned, being partially internal and partially external, and pos- 

 sibly growing in both directions from the original basal layer. The 

 filaments, however, being more or less parallel and having the goni- 

 dangia on the outer free ends, are characters whieli have led to its 

 being placed in the genus Radaisia. 



Radaisia epiphytica Setchell et Gardner sp. nov. 

 Plate 37, figs. 10-11 



Thallis pulviniformibus in superficie hostis positis, in linea exterior! 

 ut supra visis fere cireularibus, 250-350/a diam.. 50-60ju crassis; strato 

 prostrato, aut infimo, })er ramificatione dichotoma aut subdichotoma 

 in margine f ormato ; filamentis erectis laxe adhaerentibus, gregibus 

 cellularum angularum 3-5^ diam., partione cellularum in directioni- 

 bus tribus eompositis ; contentu cellularum homogeneo, caeruleo-viridi ; 

 cellulis termiualibus, subterminalibusque in gonidangiis magnitudine 

 parvo majoribus transf ormatis ; gonidiis angularibus, 1.8-2.4/Lt diam., 

 partitionibus simultaneis. 



Thalli forming cushions on the surface of tlie host, nearly circular 

 in outline as seen from above, 250-350/t across, 50-60/^ thick ; prostrate 

 or basal layer formed by dichotomous or subdichotomous branching 

 around the margin; erect filaments loosely adherent, composed of 

 groups of angular cells, 3-5/i diam., produced by cell divisions in three 

 planes; contents homogeneous, blue-green ; teinninal and subterminal 

 cells of the vertical groups transformed into gonidangia with slight 



