WISCONSIN PHYTOPLANKTON 5 



1. GoNATozYGON MONOTAENiuM De Barv. PI. 52, Fig. 1. 



in Eabenhorst, Die Algen Saciisens, Dec. 53; No. 536. 1856. 



Gonatozygon Salfsii De Bary, Unteis. u. d. Farn. d. Conj. 76, pi. 4, figs. 2.']-25. 

 1858. 



Cells usually quite long, cylindrical, length 25-30 times the breadth, 

 apices somewhat dilated and truncate, angles slightly rounded. Cell 

 wall minutely granulate except at extreme ends of cells. Chloroplasts 

 axial and with about ten pyrenoids. (Tychoplanktont.) 



Zygospores spherical, with smooth walls (De Bary). 



Length 370-408 /a; breadth of median portion 8-11.5 /x, breadth 



apices 11-15 /x. 



Diameter zygospores 25-28 /* (De Bary). 

 Crab (rrr). 



2. Gonatozygon pilosum Wolle. PI. 52, Fig. 2. 



BuU. Torr. Bot. CI. 9: 27, pi. 13, fig. 16. 1882; W. & G. S. West, Monogr. Brit. 

 Desm. 1: 34, pi. 1, figs. 19-20. 1904. 



Length about eighteen times the breadth; cell apices very slightly 

 dilated, truncate, with angles slightly rounded. Cell wall very densely 

 covered with very short, hair-like spicules. Chloroplasts axial, with 

 about six pyrenoids. (Tychoplanktont.) 



Zygospores unknown. 



Length 142 fi ; breadth without spines 7.5 fx ; length spines 1-1.5 /*. 



Eudolph (rrr). 



3. Gonatozygon aculeatum Hastings. PI. 52, Fig. 3. 



Am. Mo. Micr, Jour. 13: 29 (witli text figure). 1892; W. & G. S. West, Trans. 

 Linn. Soc. 2nd. Ser. Bot. 5: 230, pi. 12, figs. 1-2. 1896. 



Cells fairly long, cylindrical, length 15-20 times the breadth (with- 

 out spines) ; apices somewhat dilated and truncate, apical angles very 

 slightly rounded. Cell wall densely clothed with small, sharp, erect 

 spines; truncate ends without spines. Chloroplasts with 6-9 pyre- 

 noids. (Tychoplanktont.) 



Zygospores unknown. 



Length 211-212 fi; breadth of median portion 12.5 |u.; breadth of 



apices 15-22 (i ; length of spines 4.5-9.5 ft. 

 Bear (rrr), Dummy (rrr). 



SPIROTAENIA De Brebisson 1848. 



Cells of variable size, length at least five times the breadth, neither 

 constricted nor compressed ; cells usually cylindrical and with parallel 

 sides, more rarely with sides attenuated or fusiform ; poles commonly 

 broadly rounded, infrequently subacute. Cell Avail smooth and with- 

 out pores. Chloroplast a fairly broad, parietal, spirally twisted rib- 

 bon extending from pole to pole; or axial and with longitudinal 

 blades that are spirally twisted ; in either case with several pyrenoids. 

 Cell wall with no fixed point at which division takes place. 



Zygospores generally spherical ; with smooth, areolate, or short- 

 spined walls. 



