608 Cushman: Desmids from New England 



5 



Length 71//; breadth 37//; isthmus 33//. Occasional, St. 



Anthony. 



NETRIUM Nag. 1849 



6. Netrium Digitus (Ehrenb.) Itzigs. & Rothe. 



Length 160-190//; breadth 63-80//. Common at Roseau 

 Rue and St. Anthony. The prevailing form is short and much 

 swollen, at the central portion, thence narrowing fairly rapidly to 



the apex. 



7. Netrium Naegelii (Breb.) W. & G. S. West. 



Length 140-145 // ; breadth 37 /*. Occasional, Bay of 

 Islands and St. Anthony. 



PENIUM Breb. 1844 



- 



8. Penium Libellula intermedium Roy & Biss. 



Length 98-1 10 ft; breadth 24—29/*. Occasional, Rose.au 



Rue. 



CLOSTERIUM Nitzsch. 18 17 



9. Closterium Cynthia DeNot. 



Length 128/4; breadth 18/i; apices 5.2 /e. Occasional, St. 

 Anthony. 



10. Closterium angustatum Kiitz. 



Length 310-560//; breadth 19-23 /i; apices 12//. Fairly 

 common at St. Anthony. 



Some of the specimens of this species show very interesting 

 conditions of the surface ornamentation. One specimen, for in- 

 stance, was divided into five nearly equal portions. The central 

 portion was somewhat tumid, a character noted in many of the 

 specimens from this material. The striae on this portion were 

 very distinctly twisted laterally. The end segments show, even 

 more distinctly, the twisting, subspiral arrangement of the striae. 

 This twisting is developed more fully as the ends are approached. 

 The intermediate areas of the membrane which were formed later 

 by division do not keep to the subspiral striae, but have them in 

 the normal, straight form. Nearly all the specimens from this 

 locality show more or less of the subspiral arrangement of the 

 costae. 



