34 FRESH-WATER AhGM OF THE UNITED STATES. 



European S. calcicola, from which it diflfers somewhat, however, in having its hetc 

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



IV. calidarium, Wood. 



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

 vel membranaceo, aut Isete virdi vel sordide olivaceo-viridi vel olivaceo-brunneo, irregulariter 

 profunde laciniato-sinuato, ultimo eleganter laciniato; tricbomatibus insequalibus, interdum 

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

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

 vaginis interdum obsoletis, scepius dilBuentibus; forma altera maxima, articulis globosis vel 

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



Diam. — Formse primse articuli maximi x^j^^xr unc. ; cellulae^perdurantis -^-^^^ nnc. Formse 

 seeundse articuli long. ^^Vxy to ^^Vu "nc, lat, ^^Vtr to ^^ntj. articuli globosi ggVir to j^Vxf inc. 

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

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



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

 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. 



Remarhs. — 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 Algse, 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 difiicult 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." 



