Page:Journal of botany, British and foreign, Volume 34 (1896).djvu/410

 88b ALGJE FKOM CENTRAL AFRICA. [= C. gotlandicum Wittr. v. Camhrense Turn. Desmid Notes, Natu- ralist, Nov. 1893, 345, fig. 7] in the different inclination of the inferior lateral margins, the longer superior lateral margins, and the narrower apex. 22. C. globulatum, nov. sp. (Figs. 7-8). C. minutum, 1^-plo longius quam latum, profunde constrictum, sinu linear! extreme subampliato; semicellulse semicirculares angulis basalibus leviter rotimdatis ; a vertice visas circulares ; membrana crassa, minute punctata. Long. 17 />t ; lat. 13*5 /x ; lat. isthm. 4-5 /x. Mwangadan River, S. of Fuladoga. It differs from C. affi.ne Racib. [Desmidya w I'^odrozy na oJcolo ziemi, Krakow, 1892, 3, tab. vi. fig. 25) in its deeper constriction, its much narrower sinus, its thicker membrane, and circular vertical view. 23. C. subvenustum, nov. sp. (Fig. 17). C. parvum, paullo longius quam latum, subprofunde constrictum, sinu lineari ; semi- cellulaB late truncato-pyramidatse, augulis rotundatis, lateribus tri- undulatis, apicibus retusis ; a vertice vis^e ellipticae ad medium utrobique tumore praeditae ; a latere visa9 late pyramido-ovatae ; membrana punctata. Long. 36*5 /x; lat. 32*5 /x; lat. isthm. 15 /x; crass. 22 /x. Mwangadan River, S. of Fuladoga. This differs from C. venustum (Breb.) Arch. [= C. Camhricum Cke. & Wills] in its much broader cells, its broader isthmus, and in the median tumours of the vertical view. 24. Staurastrum nephroideum, nov. sp. (Fig. 13). S. par- vum, paullo longius quam latum, profunde constrictum, sinu angusto extremo subampliato extrorsum valde aperto ; semicellulae subreniformes, dorso multe convexo; a vertice vis£e triangulares lateribus concavis, angulis subtruncatis ; membrana subcrassa densissime punctata. Long. 38 /x; lat. 35 /x; lat. isthm. 11-5 /x. Mwangadan River, S. of Fuladoga. 25. S. subdilatatum, nov. sp. (Fig. 16). S. parvum, paullo longius quam latum, profunde constrictum, sinu aperto extremo rotundato ; semicellulae elliptico oblongae, apicibus subtruncatis ; a vertice visas triangulares, lateribus concavis, angulis rotundatis ; membrana dense et delicate granulata. Long. 26-5-27*5 /x; lat. 23-25 /x; lat. isthm. 9*5 /x. Mwangadan River, S. of Fuladoga. This Staurastrum appears to be nearest to 8. dilatatum Ehrnb., from which it differs in being relatively longer in proportion to its breadth, and in having more numerous granules, which are not arranged in transverse series across the angles. Pediastre-s:. 26. Pediastrum Boryanum (Turp.) Menegh. ; Ralfs, Brit. Desm. 187, tab. 31, fig. 9. Var. GRANULATUM (Kiitz.) A. Br. Forma cellulis periphericis processibus delicatissimis instructis. Diam. cell, peripher. 18-21 /x. Mwangadan River, S. of Fuladoga.