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Micrasterias pseudofurcata y n, sp. M. magna, 

 levis; semicellulis trilobis; lobis basalibus attenuatis, pro- 

 tunde incisis ; lobulis plus minus divex-gentibus, apice biden 

 t'atis; lobo polari anguste cuneato; angulis longe sub-rectis 

 productisj apice trifurcatis. Diam. .006" — .007". Hab. 

 Ponds, New Jersey and Florida. This form is similar to 

 M. iurcata, Ag., but difters in the absenee of tbe 

 middle lobe, 



Micrasterias t riangularis, n. sp. M. permagna, 

 orbicularis; semicellulis quinquelobis; lobo polari triangulari, 

 lateralibus rectis vel leviter undulatis, subaequalibus, angulis, 

 lateris in mucronem productis; lobulis et lobis intennediis 

 aequalibus, repetito-bilobulatis; lobulis bifurcatis, angulis 

 cum spinis curvato-divergentibus elongatis armatis. Diam. 

 .009" — .01". Hab. In pond on ßroadtop Mountain, Pa. 

 The lobules next the sinus, and noxt tlie polar lobe are not 



unfrequently a simple point, not bifurcate. 



Cosmarium margaritum, n. sp. C. parvum, varia- 

 bile, suborbiculare, modo depressum, modo ad tertiam longius 

 quam latius; sinu anguste lineari; semicellulis suborbiculari- 

 bus, ambitu undulato-crenatis, crenis lateribus plerumque 

 triundulatis, scrobiculis basalibus modiee instructis; dorso 

 convexis nonnunquam retusis; a vertice visis ovalibus, medio 

 ventricosis inflatis; cytiodermate leve ut margarita nitente. 

 Zygosporis sphaericis, spinis elongatis apice bifidifl obsitis. 

 Diam. .0009" — .001". Hab. Splitrock Pond, New Jersey. 

 This plant might pass fbr a variety of C. venustum, Breb, 

 or C. Naegelianum, Breb., bad tbe end no central In- 

 flation. G\ phaseolus, Breb. possesses the inflations, but 

 is entire. 



Cosmarium Donnellii, n. sp. C. mediocre, plerum- 

 que fem tarn longumquam latum, suborbiculare, sinu anguste- 

 lineari; semicellulis subseraicinularibus, dorso plus minus 

 depressis, margine circiter 18 margaritis ovalibus, in series 

 singulas, composito. Diam. et lat. .0015"— .0018". Hab. 

 Ponds, Florida. Collected by Capt. J. Donnell Smith, 1879. 

 This species comes nearest C. monomazum, Lund, but is 

 a distinct form. 



Staurastrum odontatum, n. sp. St. magnum, tarn 

 longum quam latum; semicellulis a fronte visis, quadrangu- 

 laribus angulis superioribus in cornu gracile elongatis, in- 

 curvis vel rectis, marginibus plus minus profunde serrato- 

 dentatis in apicem furcatum productis; angulis inferioribus 

 dentibus armatis, a vertice visis quadriradiatis. Diam. sine 

 rad. .0008"— .001"; cum rad., 0016"— .003"; long. .0016" 

 .0018". Hab. Splitrock Fond, New Jersey, July, 1880. 



