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€ 296 15.Zygnema. 1. HYDROPHYTZ. Pi. cell. aph. 
F. Consucatiwex. Thallus cylindrical, threadlike, 
‘tubular, jointed; coupling laterally, either by pushing out 
‘a transverse tube from the middle of the joint, or by uniting 
at the angles; spore one in each joint.—Fresh-water, green. 
XV. 15. ZYGNEMA. Agardh. Zygneme. 
Thallus threadlike, simple, tubular ; jointed; coupling 
-sparallelly by a short traverse tube emitted from the middle 
~~<f each joint, through which the granules in the joints of 
BS 
Re 
one plant pass into the opposite joint of the other plant, 
and there form a single spherical spore; granules form- 
is dng spots in each joint. 
1. Zygnema pectinatum. Comblike zygneme. 
Threads shining, rather longer than broad; spots two, 
, oblong or 3- topteds in each joint. 
Conjugata pectinata, Vaucher, 77. 
Zygnema pectinatum, Agardh Syn. 102. 
Conferva pectinata, De Candolle Fl. Fr. 2,56; Engl. Bot, 1610. 
On stones, or floating i In running waters. 
Tufts light green, crowing blackish ; spore spherical, 
lodged in the transverse tube, according to Agardh. 
B. confluens. Joints as long as broad; spots dense and 
nearly confluent. 
Conferva bipurctata, Dillw. 2. " 
: 2. Zygnema bipunctatum. Two-dotied xygneme. 
*- Threads shining, twice as long as broad; spots 2, stellate. 
Conferva Re Gch, Roth Cat. 2, 204; not of Engl, Bot. 
Conferva Stellina, Muller in N. Act. Petr. 3,93. 
Conferva cruciata, De Candolle Fl. Fr. 2, 56. 
‘  Conjugata stellina, Vaucher, 75. . 
~>Conjagata cruciata, Vaucher, 76. 
Zygnema cruciatum, 4gardh Syn. 102. 
Ditches and stagnant waters. 
Tufts entangled, floating ; spots starlike, radiated or 
= angular. 
B. gr acile. Joints three times as long as broad; shee 2 
roundish. 
Conjugata gracilis, Vaucher, 73. 
Conferva gracilis, De Candolle Fl. Fr. 2, 55. 
Zygnema gracilis? dAgardh Syn. 103. 
“" y. unipunctatum. « Joints as long’ as broad; spot 1, 
es roundish. 
