OF THE DESMIDIE.E. 



T2\ 



or deeply incised; end lobe narrow, 

 seldom and but very slightly exserted. 

 {a, h, c.) 



M. Torreyi (Bail.). — Frond smooth; 

 segments 5-lobed; basal lobes bifid, 

 middle lobes trifid, the subdivisions 

 neai'est the opposite segments and those 

 nearest the terminal lobe bideidafe at the 

 apex ; tlie intennediate three terminat- 

 ing in acute points ; all somewhat injlated 

 and tapering ; tenninal lobe narrow, not 

 exserted, spreading at the angles into 

 divergent tapering points ; ends slightly 

 emarginate. U.S.A. 



M. denticidata (Breb.). — Frond orbicu- 

 lar, smooth ; segments o-lobed; basal and 

 middle lobes twice dichotomous; idti- 

 mate subdivisions truncato- emarginate, 

 with rounded angles ; end lobe simply 

 thrice emarginate. Sporangium orbicu- 

 lar, beset with scattered stout elongate 

 spines, at first simple and obtuse, after- 

 wards forked or tiifid, their divisions 

 finally again branched and recurved. L. 

 1-113", B. 1-138". (II. 22, sporang-ium). 

 =1 Euastrum Rota (Elir.) in part. G.B., 

 I., F., G., Italy, U.S.A. /3, ends broader, 

 slightly hii'sute at the terminal margin 

 (BaUey). 



M. rotata (Ralfs). — Frond orbicular, 

 smooth ; segments 5-lobed ; basal lobes 

 twice, middle lobes thrice dichotomous ; 

 ultimate subdivisions acutely hidentate; 

 end lobe very slightly exserted, its 

 angles very slightly produced, bidentate, 

 ends emarginate. In transverse view is 

 seen an inflated protuberance just over 

 the central isthmus, which may possibly 

 exist in other species of Micrasterias. 

 L. 1-91", B. 1-104". (i. 20.) = Euastru7n 

 -Ro!!«(Ehr.,Nag.) in part; Eutomia rotata 

 (Han-ey). G.B., I., F., G., Italy, U.S.A. 



M. jimhriata (Ralfs). — Frond orbicu- 

 lar, smooth ; segments 5-lobed ; basal 

 lobes twice, middle lobes generally thrice 

 dichotomous ; idtimate subdivisions ob- 

 tusely emarginate, each furnished with 

 two curved acute sjnnes ; end lobe some- 

 what exserted, the angles slightly pro- 

 duced and rounded, and each fm-nished 

 with two or three minute spines ; ends 

 concave. L. 1-108", B. l-Ud".=Euas- 

 trum Rota (Ehr.) in part. G. B., U. S. A. 



M. apiculata (Menegh.). — Frond orbi- 

 cular, hispid all over with scattered spines ; 

 segments 5-lobed ; basal and middle lobes 

 once or twice incised, their external mar- 

 gin toothed, ultimate subdivisions fur- 

 nished with two acute spines ; end lobe 

 narrow, spinous on external margin. = 

 Euastrum aculeatum (Ehr.). G., 1?\ 



M. radiosa (Ag.). — Frond orbicular, 

 smooth ; segments 5-lobed ; basal lobes 

 twice, middle lobes generally thrice di- 

 chotomous, ultimate subdi\dsions injlated, 

 attenuate towards the end, bidentate ; end- 

 lobe emarginate, its angles dentate, (i. 

 21.) L. 1-138" ; B. ^-1^". = Euastrum 

 Sol (Ehr.). G. B., I., F., U. S. A. 



M. jjapillifera (Breb.). — Frond orbicu- 

 lar, having the principal sinuses bordered 

 by a row of minute granules, otherwise 

 smooth ; segments 5-lobed ; basal and 

 middle lobes twice dichotomous, their 

 idtimate shallow subdivisions terminated 

 by two, sometimes three, gland-like teeth j 

 end-lobe emarginate, its angles dentate. 

 Sporangium as in M. denticulata, but con- 

 siderably smaller. L. l-22r'-l-205" ; 

 B.l-238"-l-211". (i. 18, spor. 19). G.B., 

 I., F., U.S.A. 



4t Frond orbicular; segments 5-lobed; 

 lobes approximate, the intervals be- 

 tween the lobes shallow narrow inci- 

 sions ; the lateral lobes dentate, crenate, 

 or slightly sinuate; end lobe broad, not 

 exserted. {a'^b, c.) 



M. quadragies-cuspidata (Ealfs). — 

 Frond hispid all over with scattered minute 

 hair-like spines ; segments 5-lobed ; basal 

 and middle lobes slightly bipartite, their 

 subdivisions bidentate; end lobe very 

 broad, cuneate, ti-uncate, its angles biden- 

 tate. = Cosmarium quadragies-cusjndaimn 

 (Corda). G. 



M. truncata (Breb.). — Frond orbicidar, 

 smooth; segments 5-lobed; basal and 

 middle lobes obscurely bipartite, extre- 

 mities bidentate ; end lobe very broadly 

 cuneate, bidentate at the angles, and with 

 a slight central conca\'ity. L. 1-240" ; B. 

 1-250".= Cosmarium truncatum (Corda); 

 Euastrum Rota (Ehr.) in part ; 31. semi- 

 radiata (Kg.) ; Euastrum semiradiatum 

 (Nag.). G.B., I., G., F., U.S.A. 



M. crenata (Breb.). — Frond orbicidar, 

 smooth ; segments 5-lobed ; basal and 

 middle lobes usually crenate, or sinuate ; 

 end-lobe very broadly cuneate, rounded 

 at the ends, entire. L. 1-244" ; B. 1-263". 

 G. B., I., U. S. A. 



5t Frond oblong, elliptic; segments 5- 

 lobed ; lobes approximate or spreading, 

 intervals between the lobes linear or 

 somewhat sinuous, all the lobes similar 

 at the extremities, the end lobe the 

 broadest, (a, b, <?.) 



M. Jenneri (Ralfs). — Frond oblong, 

 minutely granulated; segments 5-lobed; 

 ba^al, middle, and end lobes cimeate, 



