138 FRESH-WATER ALG^E OF THE UNITED STATES. 



Damp walls ; shaded brick pavements, particularly abun- 

 dant late in the season in cold, wet weather. Have gathered 

 it in fine condition covered with snow and ice. Develops 

 from cells known as Protococcus viridis. 



Plate CXIX, figs. 1, 2, germinating spores and young 

 filaments. 



ULOTHRIX (Hormidium) VARIA, Kg. 



Yellowish green, filaments somewhat variable in thickness, 

 averaging about 7 yw. Cells as long as wide or a little longer 

 or shorter. 



Forms thin strata on moist clay soil ; found it also in large 

 pieces, several feet in extent, on moist sandy soil. Fila- 

 ments have here and there series of larger sporangium-like 

 cells. 



Plate CXIX, figs. 3-7, simple filaments, and two with 

 series sporangia, (?) 



ULOTHRIX (Hormidium) PARIETINA, (Vauch.) Kg. 



Bright yellowish green, flexuous and interwoven ; cells 

 half as long as broad ; cell membrane thin, hyaline, homo- 

 geneous. 



Diameter of filaments, 10-16 yw. 



Syn. Hormidium parietinum, Kg.; Oscillatoria parietina, Vauch. 



Shaded ground, at the base of trees, etc. 



Plate CXIX, figs. 8-10, young forms developing from 

 spores, (Protococcus cells,) which usually abound with the 

 filaments. Figs. 11-15, parts of filaments. 



ULOTHRIX (Hormidium) LENORMANDI, Kg. 



Bather dark green, mucous, attains a length of four 

 inches, floating. Diameter of filaments, 17-25 /x, articula- 

 tion one, to one-fourth diameter long; membrane rather 

 firm, often distinctly lamellate, usually constricted at the 

 joints. 



Collected by C. G. Pringle, Beam Lake, Canada. 



Plate CXIX, figs. 19, 20. 



Have quoted this diagnosis from Eabenhorst's Flora Alga- 

 rum. It describes parts of the plant satisfactorily, but there 

 is a feature not noticed ; the filaments divide repeatedly 

 longitudinally. The specimen illustrated shows how a 



