FRESH-WATER ALG^ OP THE UNITED STATES. 147 



Syn. — M. Jenneri, Ralfs, British Desmidieae, p. 16. 



Ecib. — Prope Philadelphia ; Wood. South Carolina ; (Ravenel) 



Large, oblong, for the most part finely granulate ; semicells 5-lobed ; lobes wedge-shaped ; basal 

 and intermediate, about equally broad ; end lobe broadly truncate or broadly rounded, in the 

 middle sometimes slightly and obtusely emarginate, sometimes rather deeply emarginate. 



Bemarhs. — I have found this species near Philadelphia, and also received it from 

 •Prof. Ravenel, hy whom it was collected in South Carolina. The American plant 

 differs from the typical form i not having the ultimate lobules emarginate, they 

 being merely a little hollowed out in the centre, and sometimes scarcely this. The 

 angles in some specimens are also more acute. Mr. Archer, however, speaks of a 

 variety occurring in England, in which these lobules are not emarginate, and I do 

 not think characters can be found separating the American from the European 

 forms. The median suture is in all the specimens very narrow and deep, a mere 

 line, as it were, -extending nearly to the centre. 



Fig. 7, pi. 13, represents a frond of this species. 



M. Torreyi, Bailey. 



M. permagna, oblongo-orbicularis, Isevis, profundissime lobata; semicellulis quinquelobis, lobis 

 basalibus profunde bifidis, laciniis inferioribus apice bidentatis, superioribus integris, lobis in- 

 termediis profunde trifidis, laciniis superioribus bidentatis, inferioribus integris, lac. omnibus 

 lanceolatis acuminatis, inferioribus paulum incurvis, superioribus recurvis ; lobo polari non 

 prominente, e basi angusta seusim dilatato, in vertice acute sinuato, angulis integris acumin- 

 atis. (R.) Species mihi ignoia. 



Syn. — M. Tqrreyi, Bailey. Ralps, Brit. Desmidiese, p. 210. 



Sab. — Prope Princetown, New Jersey ; Bailey. 



Frond smooth ; segments 5-lobed ; basal lobes bifid, middle lobes trifid, the subdivisions nearest 

 the opposite segments and those nearest the terminal lobe bidentate at the apex ; the inter- 

 mediate three terminating in acute points ; all somewhat inflated and tapering ; terminal 

 lobe narrow, not exserted, spreading at the angles into divergent tapering points, ends 

 slightly emarginate. (A.) 



M. foliacea, Bailey. 



M. parva, subquadrata, laevis ; semicellulis trilobis, lobis lateralibus profunde bifidis (unde rec- 

 tior semicell. quinquelobae), lobulis insequaliter inciso-dentatis, lobulis inferioribus rectis, 

 superioribus recurvis; lobo polari plus minus prominente, anguste cuneato, in vertice plus 

 minusve emarginato, angulis aut acutis integris aut productis, bidentatis. R. Species mihi 

 ignota. 



Syn. M. foliacea, Bailey. Ralps, British Desmidiese, p. 210. 



Eab. — " Worden's Pond, Rhode Island; Bailey." 



Frond subquadrate, smooth ; segments 3-lobed ; lateral lobes deeply bipartite, inciso-dentate, 

 their margins concave, inciso-serrate ; end lobe broad, cuneate, and exserted, bipartite at the 

 angles, the subdivisions narrow, and minutely dentate at the extremities ; end concave. (A.) 



Genus STAUEASTRUM, Meten. 



Cellulae libere natantes, in medio plus minus profunde constrictiB ; semicellulae a vertice 3-6 angu- 

 lares vel radiatse. Cytioderma aut Iseve aut punctatum aut verrucosum aut aculeatum, nonnnnquam 

 ciliis vel pilis obsessum. 



Cells swimming free, more or less profoundly constricted in the middle ; semicells when seen 

 from the vertex 3 to 6 angular or radiate. Cytioderm either smooth or punctate, or verrucose or 

 aculeate, sometimes covered with hairs or cilia. 



