230 FRESH-WATEE ALG^ OF THE UNITED STATES. 



Genus 75, MESOCABPTJS, Hass. 



Spores spherical or oval, between two cylindrical, straight or 

 slightly inbent cells. Copulation scalariform. 



Spore membrane smooth. 



MESOCARPUS SCALARIS, (Hass.) D. By. 



Diameter of vegetative filaments, 25-30 /t ; cells 2-6 times 

 longer than broad ; spores spherical or broadly oval, mem- 

 brane brown, smooth, nearly the same in diameter as the 

 filaments. 



Syn. Mesocarpus intricatus, Hass. ; Sphaerocarpus intricatus, Hass. 

 Frequent in marsh and meadow pools. 



Plate CXLVII, fig. 2, conjugated filaments with spores; 

 fig. 3, a specimen from Plaiuville, Conn., 1879, noted at the 

 time as variety M. scalciris. Have seen no specimens since, 

 and question, may it be a Mougeotia ? 



MESOCARPUS PARVULUS, (Hass. ) D. By. 



Diameter of filaments, 8-10 yw ; cells 6-12-16 times as long 

 as broad ; spores globose, brown at maturity ; membrane 

 smooth. Filaments of fruiting cells usually straight, but 

 sometimes arched between the spores. 



Syn. Sphaerocarpus parvulus, Hass. ; Mougeotia splendens, Kg. ; 

 Mesocarpus angustatus, Hass. 

 Ponds and pools, North, West and South. 



Plate CXLVIII, figs. 3, 4, ordinary form of fruiting fila- 

 ments. 



MESOCARPUS MACROSPORA, Wolle. 



Diameter of vegetative filaments averages about 30 yw; 

 cells 6-10 times longer than broad ; spores nearly or quite 

 twice the diameter of the filaments ; filaments arched be- 

 tween the spores. Membrane of spores smooth. 



Shallow waters, Susquehanna River, Harrisburg, Pa. 

 Plate CXLYII, fig. 4, specimen of spores and filaments. 



MESOCARPUS CRASSA, Wolle. 



Diameter of vegetative filaments, about 50 ^ ; cells 4-5, 

 or before division sometimes ten times longer than broad. 

 Spores spherical, membrane smooth, diameter averages 65 yw, 

 about one-third more than that of the filaments. 



In large light yellowish green masses, floating on stagnant 

 waters in ditches in Tocoi marshes, near St. Augustine, 

 Florida. 



Plate CXLVII, fig. 1, spores and cells of filaments. 



