ENTEROMORPHA. 107 



PRASIOLA MEXICANA, Liebm. 



Thallus 1-3 inches long and broad, margins lobately undu- 

 late ; areolas distinctly seriate ; cells somewhat quadran 

 gular, angles rounded, 6-8 yw diameter, arranged in fours ; 

 bright vegetative green, attached to rocks in rapid stream. 



The specimens examined were collected by T. S. Bran- 

 degee, in 1877, in a high mountain stream, 9,000 feet eleva- 

 tion, Colorado. 



Plate XCI, fig. 24. 



No doubt more forms of Prasiola will be identified as the 

 country is more thoroughly explored. Compare notes under 

 Ulothrix Lenormandi. 



Thallm membranaceous, vesieulose or tubulose. 



Genus 15, ENTEROMORPHA, Link. 



Thallus membranaceous, tubular or utricle-shaped, fixed at 

 the base when young, afterwards floating ; composed of one 

 stratum of cells, sometimes branched. 



Propagation by zoogonidia produced by repeated division of 

 the cytioplasni, rostrate at one extremity and furnished with 

 two cilia3. 



ENTEROMORPHA INTESTINALIS, (Linn.) Link. 



Pale or darker green, fronds simple, elongated ; variable 

 in size and form, usually becoming more or less inflated, 

 obtusely rounded above, attenuated at the base. Cells of 

 fronds 3-5-6 angled. Diameter of cells 12-20 p. 



Syn. Tremula marina tubulosa, Dill.; IBfater. spermatoidea, Kg.; 

 Solenia intestinalis, Jurg. ; Ulva intestinalis, Linn. 



In ditches, brackish water, near the sea coast. Western 

 salt-water lakes. Salt Lake, Utah. It appears to grow in- 

 differently in salt, and in fresh water. 



Plate CXXV, fig. 9, a younger frond ; fig. 10, specimen 

 of arrangement of cells. 



ENTEROMORPHA COMPRESSA, (Linn.) Grev. 



Thallus compressed tubular 5 pale, herbaceous or darker 

 green, usually simple filaments, sometimes branched ; ends 

 obtusely rounded and often inflated, tapering at the base. 

 Fructification in the cells of the membrane of which the 

 frond is composed. 



