62 



4- Collection at Scarsdale 



This material is interesting because the collection was made 

 after a thin sheet of ice had commenced to form over the water. 

 Although thus quite late in the season, a considerable desmid 

 flora was found, which consisted mainly of Closteria. The 

 material was secured from the sediment at the bottom of a 

 shallow pond near the Bronx River Parkway. The following 

 species were identified: 



Penium margaritaceum (Ehrenb.) Breb.^ — Only one specimen. 



Closterium acutum (Lyng.) Breb. — Rare. 



Closteriwn ahrupium West — Rare. 



Closterium Dianae Ehrenb. — Common. 



Closterium Cynthia DeNot — ^Very common. 



Closterium didymotocum Corda — Abundant. 



Closterium Ehrenbergii Menegh. — Common. 



Closterium Lunula (Miill.) Nitzsch. — Common. 



Closterium moniliferum (Bory) Ehrenb. — Abundant. 



Closterium tumidum Johnson — Rare. 



Pleurotaenium truncatum (Breb.) Nag. — Common. 



Euastrtim ansatum Ralfs — Rare. 



Euastrum hidentatum Nag.- — Rare. 



Euastrum oblongum (Grev.) Ralfs — Only one specimen. 



Cosmarium moniliforme Ralfs — Rare. 



Cosmarium octhodes Nordst— Rare. 



Cosmarium punctulatum Br6b. — Rare. 



Cosmarium. repandum minor West & G. S. West — Rare. 



Cosmarium undulatum Corda — Occasional. 



Arthrodesmus covergens Ehrenb. — Only one specimen. 



Staurastrum crenulatum Nag. — Only one specimen. 



The preceding report includes 50 species of desmids, of which 

 there are 15 Cosmaria, 14 Closteria, 6 Micrasterias and 5 Eu- 

 astra. 



Hartsdale, N. Y. 



