May, 1905.] A Few Ohio Desmids. 349 



A FEW OHIO DESMIDS. 



Joseph A. Cushman. 



During the spring of 1904 Mr. Charles B. Ames kindly made 

 a few collections containing desmids and sent them to me for 

 identification. These were from bodies of still water about 

 Youngstown, Ohio. Although there is but one undescribed 

 species and the total number of species small, the collection 

 showed a few points of decided interest. It considerably 

 extends our knowledge of the range of several species and varie- 

 ties, certain of which are not generally known in America. It 

 also adds to the desmid records for the state of Ohio. The- 

 following were identified from the collections: 



Netrium Digitus (Ehrenb.) Itzigs & Rothe. 



Length 260/(: breadth GS/c breadth at apex 28/(. Common. 

 In ah characters the specimens of this species were typical. 



Netrium Nagelii (Breb.) W. & G. S. West. 



Length 142/(: breadth 34/'.: breadth at apex 14/'.. Occasional. 



The only other record for this species in North America is that of the- 



writer, from the White Mountain Region of New Hampshire. 



Penium margaritaceum (Ehrenb.) Breb. var. obesum var. nov. 

 Length 57/« : breadth 22/(. Occasional. 



This has the usual characters for this species but is very much- 

 shorter and stouter than typical specimens. 



Closterium striolatum Ehrenb. 



Length SOo/c breadth 44/(: breadth at apex ll/.(. Frequent. 



Closterium Dianae Ehrenb., var. arcuatum (Breb.) Rabenh. 



Distance between apices llO/c breadth IS/t. Occasional. 

 Closterium moniliferum (Bory) Ehrenb. 



Length 25U/t: breadth 37/(: breadth at apex Sjli. 



A somewhat small form but the size is constant through the species- 



as represented in this collection. 



Closterium Lunula (Mull.) Nitzsch. 



Length 540/i: breadth 96/(. Occasional. 



Specimens of this species were of the typical form. 

 Closterium decorum Breb. 



Length 345/z: breadth 25/t: breadth at apex 5,«. Frequent. 



Specimens of this species, like those of C. monilifenini, of less than the 



usual size although in other ways they were typical. 



Pleurotaenium coronatum (Breb.) Rabenh., var. nodulosum (Breb,) West. 

 Length 527-560/.'; breadth at base 47-65/i: breadth at apex 25-46/t. 

 Common. Specimens of this variety were longer than those usually 

 met with and they vary considerably in size, in breadth of apex and 

 in the number of the crenulations. 



Pleurotaenium Trabecula (Ehrenb.) Nag., forma clavata (Kutz.) West. 

 ^ Length 288/'.: breadth at base 34/(: breadth at apex 19/( 



Common in the collections.'; 

 var.frectum (Delp.) West. 



Length 280/(: breadth at base IS/c breadth at apex 13/(. Common.. 



Cell wall smooth. 



