50 FRESH-WATER ALGLE OF THE UNITED STATES. 



CLASS III. CYANOPHYCE^E. 

 ORDER VI. SCHIZOSPOHE.E. 



FAMILY XVIII. Nostocacese. 



Section a.RIVULARIE^. 



Genus 81. Calothrix. 

 " 82. Mastigonema. 

 " 83. Isactis. 

 " 84. Gloeotrichia. 

 " 85. Rivularia. 



Section b.SCYTONEMEJE. 



Genus 86. Scytonema. 



" 87. Symphyosiphon. 

 " 88. Tolypothrix. 

 " 89. Plectonema. 

 " 90. Petalonema. 



Section c.SIROSIPHONE^E. 



Genus 91. Sirosiphon. 

 " 92. Hapalosiphon. 



Section d.NOSTOCE^E. 



Genus 93. Nostoc. 

 " 94. Anabaena. 

 " 95. Sphaerozyga. 

 " 96. Aphaiiizomenoii. 

 " 97. Nodularia. 

 " 98. Cyliiidrospermum. 



Section e.OSCILLARIE^. 



Genus 99. Chamaesiphon. 



" 100. Lyngbya. 



" 101. Symploca. 



" 102. Mierocoleus. 



" 103. Oscillaria. 



" 104. Beggiatoa. 



" 105. Leptothrix. 



" 106. Spiruliiia. 



" 107. Spirillum. 



FAMILY XIX. Chroococcacese. 



Genus 108. Gloeothece. 

 " 109. Aphanothece. 

 " 110. Syriechococcus. 



111. Merismopedia. 

 " 112. Coelosphaerium. 

 ' 113. Clathrocystis. 

 " 114. Gomphosphaeria. 

 " 115. Microcystis. 

 " 116. Anacystis. 

 44 117. Polycystis. 



118. Gloeocapsa. 



119. Aphanocapsa. 

 " 120. Chroococcus. 



