SPECIES OF DESMIDS. 



8l 



5. Leptozosma. 

 An immature form of Desmidium, 6. 



6. Desmidium. Fig. 6. 

 I. Mucous sheath present . . 

 I. Mucous sheath absent (a), 

 a. Cells united by their entire end margins {b). 



a. Cells united by the outer portions of the ends (</). 



b. Cells nearly twice as long as broad . . 

 b. Cells less than twice as long as broad (c). 



Celjs in side view quadrate qtiadratutn, 26; quadratigulatum, 27 



cyliiidricum, 25 



lonsatiim, 26 



Swartzii, 26 



diagonum, \e^<) 



Baileyi, 2 7 



Nordstedtianiim, 28 



Cells in side view triangular . . . 



Borders crenate or undulate aptogonmm, 27; 



Borders straight, filament twisted 



7. Phymatgdocis. Fig. 7, 

 One species 



8. SphjErozosma. Fig. 8. 



1. Cells twice broader than long, lobes not constricted (a). 



1. " " " " lobes constricted near the end, 



constrictum 



2. Cells twice longer than broad, in sheath or not excavatum, 

 2. Cells less than twice longer than broad (b). 



a. Cells closely approximate, ends rounded 



a. " " " ends truncate, concave, 



a. Cells more or less remote, ends rounded . . 



b. Ends pointed; semi-cells remote; sinus deep, wide. 



29 



b. Ends rounded, spinous; cells slightly constricted. 



. pulchrum, 29 



rectangiilare, 3 1 



vertebraium, 30 



nioiiilifonne.** 



spinulosum, 31 



b. Ends rounded, not spinous; cells deeply constricted, filifornie, 29 



Wallachii, 30 

 pitkkelhim.** 



b. End truncate, concave 



b. Ends truncate, not concave 



fig. 



FIG. 10. 



serratuin, 30 

 NordstedtianHm.\ 



9. onychonema.* 



1. Cells with spine-like projecting ends 



2. Cells without spine-like ends 



10. MESOT/ENIUM. 



I. Cells cylindrical (a). 



I. Cells oval or elliptical, about twice longer than wide, in mucus on 

 wet wood .... . . micrococcuin, 32 



*Mr. WoUe joins this to Sphcerozosma . f Journ. R. Micr. Sec, Dec, 1885. 

 **F.-w. AlgK, .pp 23 et seq. 



