MOUGEOTIA. 227 



ZYGOGONIUM PARVULUM, Kg. 



Diameter of filaments, 22-24 // cells 4-6 times longer than 

 broad, not swollen ; zygospore globose produced in the con- 

 jugative canal; diameter very little more than that of the cells. 

 Pools and ponds. 



Syn. Zygnema ordinarium, Berk. 



The distinction between this form and Z. decussatum, is 

 slight, hardly sufficient for a good species. We quote it 

 without confidence in its value, probably a form of Z. de- 

 cussatum. 



Plate CXLV, fig. 9. 



ZYGOGONIUM RALFSII, Kg. 



Diameter of vegetative filaments, 16-20 /<<; cells 2J-3 

 (rarely 4) times as long as broad ; zygospore compressed 

 ellipsoid twice as long as broad, produced in the inflated 

 conjugative canal ; sporoderm smooth. 

 Syn. Tyndaridea Ralfsii, Hass. 



Pools, Pennsylvania ; rather rare. 

 Plate CXLY, fig. 8, part of conjugated filaments. 



The above description is from European works and de- 

 scribes our form correctly except the zygospores ; the differ- 

 ence between the length and breadth of the spore is not 

 near as great. 



Genus 74, MOUGEOTIA, D. By. 



Cells cylindrical with axile chlorophyl -plates. Copulation 

 scalariform. Zygospores drawn together in the widely swollen, 

 bladdery, persisting middle space. 



MOUGEOTIA SPHAEROCAKPA, Wolle. 



Diameter of vegetative filaments, 20-25 ^ ; cells 3-6 times 

 longer than broad; zygospores large spherical, diameter 

 about 40 /*. 



Ponds, New Jersey, Pennsylvania, Florida, etc. The 

 nearest allied species of Europe is M. laevis, Arch. Fila- 

 ments about the same diameter, but cells shorter (2 diam- 

 eters, or before division 4 diameters). Zygospores elliptic 

 or oval. Archer says, "conjugation takes place by short 

 wide processes, which, along with the shortness of the cells, 

 give the pair of conjugating filaments somewhat of the ap- 

 pearance of a perforated ribbon-like structure." He adds, 

 " The elliptic zygospore, within the inflated transverse tube, 

 has the longer diameter of the spore placed vertically to the 

 length of the filament." 



