22 WISCONSIN PHYTOPLANKTON 



SI. ( 34) Trie-homes not attenuated Family Nostocaceae 32 



22. ( 33) Filaments solitary or interwoven to form flocculent masses 



of small size Anabaena p. 55 



33. (32) Filaments laterally joined to form small plate-like colonies 



of macroscopic size Aphanizomenon p. 61 



34. ( 31) Trichomes attenuated to a hair-like point Gloeotrichia p. 63 



35. ( 1) Coloring matter in definite chromatophores 36 



36. ( 57) Chromoplasts golden brown in color .- 37 



37. ( 38) Wall heavily impregnated with silica and definitely marked 



with grooves or rows of dots Bacillarieae (see part 2). 



38. ( 37) Wall not heavily impregnated with silica 



Class Phaeophyceae 39 



39. ( 52) Cells generally motile, rarely forming palmella or rhizopo- 



dial stages Division Euchrysomonadinae 40 



40. (45) Cells with one flagellum Order Chromulinales 41 



41. ( 42) Cells naked Chrysamoeba p. 67 



42. (41) Cells with a differentiated periplast 



Family Mallomonadaceae 43 



43. ( 44 ) Cells solitary Mallomonas p. 67 



44. ( 43 ) Cells in colonies Chrysosphaerella p. G9 



45. ( 40) Cells with two flagella 46 



46. ( 47 ) Flagella of equal length Synura p. 70 



47. ( 46) Flagella of unequal length Order Ochromonadales 48 



48. ( 51) Cells in a definite receptacle Family Dinobryaceae 49 



49. ( 50) Receptacles homogeneous, without growth rings. .Dinobryon p. 72 



50. ( 49) Receptacles with successive growth rings Hyalobryon p. 75 



51. ( 48) Cells never in a definite receptacle Uroglenopsis p. 71 



52. ( 39) Cells usually immobile, rarely motile 53 



53. ( 54) Cells spherical to ovoid, embedded in a gelatinous mass.... 



Phaeococcus p. 76 



54. ( 53) Cells with pseudopodial processes 



Division Rhizochrysidinae 55 



55. ( 56) Cells solitary or in irregular colonies Rhizochrysis p. 77 



56. ( 55) Cells in a linear series Chrysidastrum p. 78 



57. ( 36) Chromoplast grass-green or yellowish-green in color 58 



58. ( 69) Chromoplast yellowish-green, with oil not starch the assimi- 



lation product Class Heterokonteae 59 



59. ( 60) Vegetative cells motile Chlorochromonas p. 80 



60. ( 59 ) Vegetative cells immobile 61 



61. ( 68) Cells solitary or in colonies, never in filaments 



Order Heterococcales 62 



62. ( 63 ) Cells epiphytic Peroniella p. 81 



63. ( 62) Cells free-floating 64 



64. ( G5) Length of cells several times the diameter Ophiocytium p. 85 



65. ( 64) Length of cells less than twice the diameter 66 



CO. ( (>7) Cells irregularly distributed throughout an ovoid, gelatinous 



envelope Chlorobotrys p. 82 



67. ( 66) Cells arranged about a common center and enclosed by an 



irregular, gelatinous envelope Botryococcus p. 33 



68. ( 61) Cells united to form simple filaments Tribonema p. 87 



69. ( 58) Chloroplast grass-green, generally with pyrenoids and starch 



Class Chlorophyceae 70 



