THE GREEN ALGAE OF NORTH AMERICA 199 



quite small chromatophores ; always in longitudinal and often 

 in transverse series. Me. to W. I. Europe. 



One of the most attractive of our Enteromorphas both in habit 

 and microscopically. There are other species which occasion- 

 ally have short monosiphonous branches, but in E. plumosa 

 nearly every young branch terminates in a monosiphonous series 

 of considerable extent. Common in northern New England, 

 growing largely on Cladophora glaucescens and on rocks and 

 shells in rock pools ; also in quiet bays. 



5. E. CLATHRATA (Roth) Greville, 1830, p. 181 ; P. B.-A., 

 No. IvXXVIII ; Ulva clathrata Farlow, 1881, p. 44. Frond fili- 

 form, cylindrical or compressed, much branched in all direc- 

 tions, the branches tapering from base to summit, but not end- 

 ing in a single series of cells ; cells rectangular, usually longer 

 than broad, always in longitudinal series, the chromatophore 

 noticeably smaller than the cell. Me. to W. I.; Alaska. 



Europe ', Tasmania, New Zealand. 



A species of warm quiet waters, where it often forms great 

 floating masses ; it differs from most other species in having a 

 real system of branching of various orders ; also in the chroma- 

 tophore smaller than the cells. From E. plumosa, which agrees 

 with it in these particulars, it differs by the absence of mono- 

 siphonous ramuli. It is common at some points in southern 

 Mass., and probably along the coast to the south ; but so many 

 forms have been included under this name in older records, that 

 few localities are certain. It is not common north of Cape Cod. 

 Ulva clathrata var. Rothiana forma prostrata Farlow, 1881, p. 44, 

 P. B.-A., No. 459, seems nearer to E.prolifera. 



6. E. CRINITA (Roth) J. G. Agardh, 1882, p. 144 ; P. B.-A., 

 Nos. 460, 965, 1325. Frond filiform, cylindrical or compressed, 

 much and repeatedly branched, the branches tapering, the 

 smallest usually of a single series of quite short cells ; cells al- 

 most always in longitudinal series, often rounded, quite or 

 nearly filled by the chromatophore. Me. to N. J.; Gulf of Mex- 

 ico, Alaska to Cal. Europe. 



In habit this common marine species resembles E. clathrata, 

 but the latter lacks the short-celled monosiphonous ramuli ; 

 monosiphonous ramuli are found in E. p/i/inosa, but the net-like 

 cells of the latter are quite distinct from the cells of E. crhiitn, 

 which resemble those of E. prolifera, though somewhat smaller. 



