34 FRESH-WATER ALGJE OF THE UNITED STATES. 



European S. calcicola, from which it differs somewhat, however, in having its hete' 

 rocysts both terminal and among the cells, and also somewhat in their size. 



IV. calidarium, WOOD. 



N. thallo maximo, indefinite expanse, ant membranaceo-coriaceo vel membranaceo-gelatinoso 

 vel raerabranaceo, aut laete virdi vel sordide olivaceo-viridi vel olivaceo-brunneo, irregulariter 

 profunde laciniato-sinuato, ultimo eleganter laciniato; trichomatibus inaequalibus, interdum 

 flexuoso-curvatis, plerumque subrectis et arete conjnnctis, in formis duabus occurrentibus : 

 forma altera parva, viridi, articulis cylindricis, cum cellulis perdurantibus hie illic interjectis, 

 vaginis interdum obsoletis, ssepius diffluentibus; forma altera maxima, articulis globosis vel 

 oblongis, aurantiaco-brunnea, cellulis perdurantibus ab articulis ceteris baud diversis. 



Diam. Formse prirnse articuli maximi j^-yy unc. ; cellulae perdurantis ^Vtf unc - Formae 

 secundae articuli long. 5 ^TJ to sinnr unc -' lat - StfVtf to ssW articuli globosi ^ir to ztjW uuc - 

 Syn. N. calidarium, WOOD, American Journal of Science and Arts, 1869. 

 Hab. "Benton Springs, Owen's Valley, California" (Mrs. Partz). 



Thallus very large, indefinitely expanded, either membrano-coriaceous or membrano-gclatinous 

 or membranaceous, either bright green or dirty olive-green or olive-brown, irregularly pro- 

 foundly laciniately sinuate, finally elegantly laciniate; filaments unequal, sometimes flexu- 

 ously curved, but mostly straightish and closely conjoined, occurring in two forms ; the 

 one small, green, with cylindrical joints, the heterocysts scattered here and there, the sheaths 

 sometimes absent, often diffluent; the other form very large, with globose or oblong articles, 

 orange-brown, the heterocysts not different from the other cells. 



Remarks. Numerous specimens of this species were received from Mrs. Partz, 

 who collected them in Benton's Spring, a thermal water situated in the extreme 

 northern point of Owen's Valley, California, sixty miles southwest from the town 

 of Aurora. The following extract from a letter of Mrs. Partz describes the place 

 and mode of their growth more minutely. 



" I send you a few samples of the singular vegetation developed in the hot springs 

 of our valley. These springs rise from the earth in an area of about eighty square 

 feet, which forms a basin or pond that pours its hot waters into a narrow creek. 

 In the basin are produced the first forms, partly at a temperature of 124 135 

 Fahr. Gradually in the creek and to a distance of 100 yards from the springs are 

 developed, at a temperature of 110 120 Fahr., the Alga?, some growing to a 

 length of over two feet, and looking like bunches of waving hair of the most beau- 

 tiful green. Below 100 Fahr., these plants cease to grow, and give way to a slimy 

 fungus growth, though likewise of a beautiful green, which, finally, as the tempera- 

 ture of the water decreases, also disappears. They are very difficult to preserve, 

 being of so soft and pulpy a nature as not to bear the least handling, and must 

 be carried in their native hot water to the house, very few at a time, and floated 

 upon paper. After being taken from the water and allowed to cool they become 

 a black pulpy mass. But more strange than the vegetable are the animal organ- 

 izations, whose germs, probably through modifications of successive generations, 

 have finally become indigenous to these strange precincts. Mr. Partz and myself 

 saw in the clear water of the basin a very sprightly spider-like creature running 

 nimbly over the ground, where the water was 124 Fahr., and on another occasion 

 dipped out two tiny red worms." 



