Calcareous Pebbles formed by Alga. 79 



Cymbella pusilla, Grun. 



(Encyonema) Cesatii, Grun. 



,, gracilis Rab. var. ? (n. sp. teste Cleve). 



Triangulum, E. 



turgida, Greg. Rare. 



ventricosa, K. 



var. obtusa, Grun. 



Denticula elegans, K. 

 Diploneis oculata Bre"b. Rare. 



ovalis, Hantzsch. Rare. 

 Epithemia Argus, E. Frequent. 

 gibba, E. 



turgida var. granulata, Grun. 



Veliei, Thomas. Cleve notes this as E. Cistula, E. var. 



proboscidea, Grun., which Grunow considers the same as 

 E. proboscidea Sm. This form is, however, much larger, 

 and has much coarser strife than E. proboscidea, either in 

 Grunow's or Smith's figures. 

 Eunotia Arcus, E. Rare. 

 praerupta, Grun. 



var. curta, Grun. Frequent. 



Fragilaria mutabilis, Grun. 

 Harrisonii, Grun. 



Gomphonema acuminatum, E. 



var. elongata, Grun. 



intricatum, K. 



lanceolatum, E. 



olivaceum, E. 



subtile, E. 



Mastogloia Grevillii, W. S. A short, broad form. 



Smithii, Thwaites var. amphicephala, Grun. 



var. lacustris, Grun. Frequent. 



Melosira crenulata var. tenuis, Grun. 

 Navicula bacilliformis, Grun. 

 brachysira, Breb. 

 cincta, K. 



var. Heufleri, Grun. 



lanceolata, K. Rare. 

 radiosa, K. Rare. 

 var. acuta, K. 



radiosa, var. tenella, Breb. 



M 



