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 2(30, u: breadth (38, u: breadth at apex 28,«. Common. 
In all characters the specimens of this species were typical. 
Netrium Nagelii (Breb.) W. & G. S. West. 
Length 142,a; breadth .34,u: breadth at apex 14,f!. 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 o7,n: breadth 22a. Occasional. 
This has the usual characters for this species but is very much 
shorter and stouter than typical specimens. 
Closterium striolatum Ehrenb. 
Length 305/n breadth 44/i: breadth at apex ll/c Frequent. 
Closterium Dianae Ehrenb., var. arcuatum (Breb.) Rabenh. 
Distance between apices 110,u: breadth 18,(!. Occasional. 
Closterium moniliferum (Bory) Ehrenb. 
Length 2.i0,u: breadth 37,«: breadth at apex 8,(t. 
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,ft. Occasional. 
Specimens of this species were of the typical form. 
Closterium decorum Breb. 
Length 345/t: breadth 25/c breadth at apex 5,«. Frequent. 
Specimens of this species, like those of C. moniliferum, of less than the 
usual size although in other ways they were typical. 
Pleurotaenium coronatum (Breb.) Rabenh., var. nodulosum (Breb,) West. 
Length 527— 5fi0/f: breadth at base 47-65,(C 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 anci 
in the number of the crenulations. 
Pleurotaenium Trabecula (Ehrenb.) Nag., forma clavata (Kutz.) West. 
Length 288fi: breadth at base 34 ,h: breadth at apex 19,u. 
Common in the collections, 
var. rectum (Delp.) West. 
Length 28Qu: breadth at base 18,u: breadth at apex 13,u. Common. 
Cell wall smooth. 
