EXPLANATIONS AND REFERENCES, 



PLATE CLXXXI. 



Figures magnified 250 diameters. 



PAGE. 



Fig. 1-4. TOLYPOTHRIX AEGAGROPILA or MUSCICOLA, . . . 263 



' 5-7. TOLYPOTHRIX TENUIS, ponds, Pennsylvania, . . 205 



" 8-11. TOLYPOTHRIX TRUNCICOLA, frequent on trunks of trees, South 



Carolina, . . . .206 



'* 12-15. PLECTONEMA MIRABILE, typical forms, limestone springs, Penn- 

 sylvania, .... 266 



